@article{Tapinaki2023,

title = {CONVENTIONAL OR AUTOMATED PHOTOGRAMMETRY FOR CULTURAL HERITAGE DOCUMENTATION?},

author = {S. Tapinaki and M. Pateraki and M. Skamantzari and A. Georgopoulos},

url = {https://doi.org/10.5194/isprs-archives-XLVIII-M-2-2023-1535-2023},

doi = {10.5194/ISPRS-ARCHIVES-XLVIII-M-2-2023-1535-2023},

issn = {1682-1750},

year  = {2023},

date = {2023-06-26},

urldate = {2023-01-01},

journal = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {XLVIII-M-2-2023},

pages = {1535-1542},

publisher = {Copernicus GmbH},

abstract = {Abstract. During the past 15 years photogrammetric practice has experienced an unprecedented change by the influence of computer vision algorithms, which support an almost completely automated processing. It is widely acknowledged that this fact has “democratized” Photogrammetry a lot, in the sense that it has become almost everyone’s tool. However, this radical change has been met by scepticism by traditional photogrammetrists, who claim that such tools may lead to geometrically wrong and inaccurate results if not accompanied by thorough projection and error checks and evaluation of the correctness of results.In this paper, the two approaches are briefly described on the basis of the geometric documentation of a cultural heritage funerary monument situated in the archaeological site of Messini in Southern Greece. An effort is made for highlighting the obvious advantages of each approach but also indicating their disadvantages. Applications, subject to different requirements and processing procedures are identified, rationalizing that conventional photogrammetric procedures still cannot be easily replaced.},

keywords = {Cultural heritage Documentation, MVS, Orthophoto, SfM, Stereoscopic photogrammetry},

pubstate = {published},

tppubtype = {article}

}

@article{Zikas2023,

title = {MAGES 4.0: Accelerating the World’s Transition to VR Training and Democratizing the Authoring of the Medical Metaverse},

author = {Paul Zikas and Antonis Protopsaltis and Nick Lydatakis and Mike Kentros and Stratos Geronikolakis and Steve Kateros and Manos Kamarianakis and Giannis Evangelou and Achilleas Filippidis and Eleni Grigoriou and Dimitris Angelis and Michail Tamiolakis and Michael Dodis and George Kokiadis and John Petropoulos and Maria Pateraki and George Papagiannakis},

doi = {10.1109/MCG.2023.3242686},

year  = {2023},

date = {2023-03-01},

urldate = {2023-03-01},

journal = {IEEE Computer Graphics and Applications},

volume = {43},

number = {2},

pages = {43-56},

keywords = {Behavioral sciences, Engines, Metaverse, Software, Task analysis, Training, visualization},

pubstate = {published},

tppubtype = {article}

}

@article{verykokou2023overview,

title = {An Overview on Image-Based and Scanner-Based 3D Modeling Technologies},

author = {Styliani Verykokou and Charalabos Ioannidis},

url = {https://www.mdpi.com/1424-8220/23/2/596},

doi = {10.3390/s23020596},

issn = {1424-8220},

year  = {2023},

date = {2023-01-04},

urldate = {2023-01-04},

journal = {Sensors},

volume = {23},

number = {2},

pages = {596},

publisher = {Multidisciplinary Digital Publishing Institute},

abstract = {Advances in the scientific fields of photogrammetry and computer vision have led to the development of automated multi-image methods that solve the problem of 3D reconstruction. Simultaneously, 3D scanners have become a common source of data acquisition for 3D modeling of real objects/scenes/human bodies. This article presents a comprehensive overview of different 3D modeling technologies that may be used to generate 3D reconstructions of outer or inner surfaces of different kinds of targets. In this context, it covers the topics of 3D modeling using images via different methods, it provides a detailed classification of 3D scanners by additionally presenting the basic operating principles of each type of scanner, and it discusses the problem of generating 3D models from scans. Finally, it outlines some applications of 3D modeling, beyond well-established topographic ones.},

keywords = {3D modeling, CBCT, CMM, CT, laser scanners, MRI, multi-view stereo, scanners, segmentation, structure from motion},

pubstate = {published},

tppubtype = {article}

}

@article{jimaging9030072,

title = {6D Object Localization in Car-Assembly Industrial Environment},

author = {Alexandra Papadaki and Maria Pateraki},

url = {https://www.mdpi.com/2313-433X/9/3/72},

doi = {10.3390/jimaging9030072},

issn = {2313-433X},

year  = {2023},

date = {2023-01-04},

urldate = {2023-01-01},

journal = {Journal of Imaging},

volume = {9},

number = {3},

abstract = {In this work, a visual object detection and localization workflow integrated into a robotic platform is presented for the 6D pose estimation of objects with challenging characteristics in terms of weak texture, surface properties and symmetries. The workflow is used as part of a module for object pose estimation deployed to a mobile robotic platform that exploits the Robot Operating System (ROS) as middleware. The objects of interest aim to support robot grasping in the context of human-robot collaboration during car door assembly in industrial manufacturing environments. In addition to the special object properties, these environments are inherently characterised by cluttered background and unfavorable illumination conditions. For the purpose of this specific application, two different datasets were collected and annotated for training a learning-based method that extracts the object pose from a single frame. The first dataset was acquired in controlled laboratory conditions and the second in the actual indoor industrial environment. Different models were trained based on the individual datasets and a combination of them were further evaluated in a number of test sequences from the actual industrial environment. The qualitative and quantitative results demonstrate the potential of the presented method in relevant industrial applications.},

keywords = {challenging object characteristics, complex scenes, industrial robotic applications, Machine Learning, object 6D pose estimation, object localization},

pubstate = {published},

tppubtype = {article}

}

@article{potsiou2022prototype,

title = {A Prototype Machine Learning Tool Aiming to Support 3D Crowdsourced Cadastral Surveying of Self-Made Cities},

author = {Chryssy Potsiou and Nikolaos Doulamis and Nikolaos Bakalos and Maria Gkeli and Charalabos Ioannidis and Selena Markouizou},

url = {https://www.mdpi.com/2073-445X/12/1/8},

doi = {10.3390/land12010008},

issn = {2073-445X},

year  = {2022},

date = {2022-12-16},

urldate = {2022-12-16},

journal = {Land},

volume = {12},

number = {1},

pages = {8},

publisher = {MDPI},

abstract = {Land administration and management systems (LAMSs) have already made progress in the field of 3D Cadastre and the visualization of complex urban properties to support property markets and provide geospatial information for the sustainable management of smart cities. However, in less developed economies, with informally developed urban areas\textemdashthe so-called self-made cities\textemdashthe 2D LAMSs are left behind. Usually, they are less effective and mainly incomplete since a large number of informal constructions remain unregistered. This paper presents the latest results of an innovative on-going research aiming to structure, test and propose a low-cost but reliable enough methodology to support the simultaneous and fast implementation of both 2D land parcel and 3D property unit registration of informal, multi-story and unregistered constructions. An Indoor Positioning System (IPS) built upon low-cost Bluetooth technology combined with an innovative machine learning algorithm and connected with a 3D LADM-based cadastral mapping mobile application are the two key components of the technical solution under investigation. The proposed solution is tested for the first floor of a multi-room office building. The main conclusions concern the potential, usability and reliability of the method.},

keywords = {3D cadastre, 3D mapping, Crowdsourcing, indoor localization, informal development, Machine Learning},

pubstate = {published},

tppubtype = {article}

}

@article{betsas_point-cloud_2022,

title = {Point-Cloud Segmentation for 3D Edge Detection and Vectorization},

author = {Thodoris Betsas and Andreas Georgopoulos},

url = {https://www.mdpi.com/2571-9408/5/4/208},

doi = {10.3390/heritage5040208},

issn = {2571-9408},

year  = {2022},

date = {2022-12-09},

journal = {Heritage},

volume = {5},

number = {4},

pages = {4037--4060},

abstract = {The creation of 2D\textendash3D architectural vector drawings constitutes a manual, labor-intensive process. The scientific community has not provided an automated approach for the production of 2D\textendash3D architectural drawings of cultural-heritage objects yet, regardless of the undoubtable need of many scientific fields. This paper presents an automated method which addresses the problem of detecting 3D edges in point clouds by leveraging a set of RGB images and their 2D edge maps. More concretely, once the 2D edge maps have been produced exploiting manual, semi-automated or automated methods, the RGB images are enriched with an extra channel containing the edge semantic information corresponding to each RGB image. The four-channel images are fed into a Structure from Motion\textendashMulti View Stereo (SfM-MVS) software and a semantically enriched dense point cloud is produced. Then, using the semantically enriched dense point cloud, the points belonging to a 3D edge are isolated from all the others based on their label value. The detected 3D edge points are decomposed into set of points belonging to each edge and fed into the 3D vectorization procedure. Finally, the 3D vectors are saved into a “.dxf” file. The previously described steps constitute the 3DPlan software, which is available on GitHub. The efficiency of the proposed software was evaluated on real-world data of cultural-heritage assets.},

note = {Number: 4 

Publisher: Multidisciplinary Digital Publishing Institute},

keywords = {3D computer vision, Cultural heritage, Edge detection, Photogrammetry, point-cloud segmentation, SfM-MVS},

pubstate = {published},

tppubtype = {article}

}

@article{betsas_3d_2022,

title = {3D EDGE DETECTION AND COMPARISON USING FOUR-CHANNEL IMAGES},

author = {T. Betsas and A. Georgopoulos},

url = {https://isprs-archives.copernicus.org/articles/XLVIII-2-W2-2022/9/2022/},

doi = {10.5194/isprs-archives-XLVIII-2-W2-2022-9-2022},

issn = {2194-9034},

year  = {2022},

date = {2022-12-08},

urldate = {2022-12-08},

journal = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {XLVIII-2/W2-2022},

pages = {9--15},

abstract = {Point cloud segmentation, is a widespread field of research and it is useful in several research topics and applications such as 3D point cloud analysis, scene understanding, semantic segmentation etc. Architectural vector drawings constitute a valuable platform source for scientists and craftsmen while the production of such drawings is time-consuming because many of the creation steps are done manually. Detecting 3D edges in point clouds could provide useful information for the automation of the creation of 3D architectural vector drawings. Hence, a 3D edge detection method is proposed and evaluated with a proof-of-concept experiment and another one using a professional software. The scope of this effort is twofold, firstly the production of semantically enriched 3D dense point clouds exploiting four-channel images in order to detect 3D edges and secondly the comparison of the detected 3D edges with their corresponding edges in a textured 3D model. Comparing 3D edges in the early step of the 3D dense point cloud production and in the final step of 3D textured mesh, provides useful conclusions of the data used for the automatic creation of 3D drawings. Both of the experiments i.e., the proof-of-concept and using the professional SfM-MVS software were conducted using real world data of cultural heritage objects.},

keywords = {3D Edge Comparison, 3D Edge Detection, Point Cloud Segmentation, SfM-MVS},

pubstate = {published},

tppubtype = {article}

}

@article{evangelou2022building,

title = {BUILDING DIGITAL TWINS FOR SMART CITIES: A CASE STUDY IN GREECE},

author = {T Evangelou and M Gkeli and C Potsiou},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/X-4-W2-2022/61/2022/},

doi = {10.5194/isprs-annals-X-4-W2-2022-61-2022},

issn = {2194-9050},

year  = {2022},

date = {2022-10-14},

journal = {ISPRS Ann. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {X-4/W2-202},

pages = {61--68},

abstract = {Abstract. The recent emergence of the Internet of Things (IoT), the latest technological innovations and the widespread use and embrace of Building Information Models (BIMs) offer several new ideas and decision-making capabilities throughout the life cycle of the built environment. The ability to connect and monitor data from sensor networks remotely in real time as well as the simulation and optimization of engineering systems, have led to the emergence of the Digital Twin (DT) concept of the structured environment. Although BIM lacks semantic completeness in areas beyond the scope of building modelling such as control systems, cadastral systems, networking of sensors, meteorological networks, etc., the DTs aim to achieve the synchronization of big data from various sources and simulate the real world into a virtual platform for the seamless management and control of the construction process, facility management, environmental monitoring, disaster management and disaster prevention, and other life cycle processes within the built environment. DTs in the built environment are still in nascent stages and thus a more in-depth investigation is required to explore and establish the best practices and technologies to serve this evolution. In this paper, we propose a methodology for providing the DT of a building; by crossing from the BIM static world to the dynamic cyber-world of DTs. A practical application is implemented for a two-storey ‘smart' building with sensor systems installed in its assets and in the surrounding landscape area. As the practical experiment is successfully completed, we conclude that such an endeavour can actually be achieved at building level offering several economic, environmental and social benefits.},

keywords = {Building Information Model (BIM), Digital Twin (DT), Internet of Things (IoT), Smart Buildings, Smart City},

pubstate = {published},

tppubtype = {article}

}

@article{apostolopoulos2022improve,

title = {How to Improve Quality of Crowdsourced Cadastral Surveys},

author = {Konstantinos Apostolopoulos and Chryssy Potsiou},

url = {https://www.mdpi.com/2073-445X/11/10/1642},

doi = {10.3390/land11101642},

issn = {2073-445X},

year  = {2022},

date = {2022-09-23},

journal = {Land},

volume = {11},

number = {10},

pages = {1642},

publisher = {MDPI},

abstract = {The potential for introducing voluntary citizen participation, combined with mobile services, for cadastral data collection for a systematic first registration has been thoroughly investigated and even implemented in some official projects. This data collection procedure can technically be ac-complished safely, but results have shown that many participants have difficulty in identifying the land parcels (location, shape and size) on the base-map (orthophoto, air-photo, etc.) correctly. Either they have to ask the assistance of a private professional, or there is a high risk that a number of errors may appear in the submitted crowdsourced data. This paper investigates how to improve the quality of such crowdsourced cadastral data, by adding to the base-map any available and relevant geospatial and descriptive information that may help the participants to correctly identify their land parcel. In particular, the research investigates and suggests (a) which types of available geospatial information should be added to the base-map and by whom (professionals or a group of trained volunteers), and (b) the necessary quality controls that must be made in the compilation of the advanced crowdsourced base-map\textemdasha case study follows to assess the suggested proposal. In addition, this paper provides an updated version of the crowdsourced methodology for cadastral surveys as modelled by the authors in an earlier stage of their research. This updated version briefly includes all quality controls needed to ensure the quality of a modern cadastre that the authors will further investigate in a subsequent stage.},

keywords = {cadastral basemap, Cadastre, Crowdsourcing, Land administration, quality controls},

pubstate = {published},

tppubtype = {article}

}

@article{SHABANI2022314,

title = {3D simulation models for developing digital twins of heritage structures: challenges and strategies},

author = {Amirhosein Shabani and Margarita Skamantzari and Sevasti Tapinaki and Andreas Georgopoulos and Vagelis Plevris and Mahdi Kioumarsi},

url = {https://www.sciencedirect.com/science/article/pii/S2452321622000981},

doi = {https://doi.org/10.1016/j.prostr.2022.01.090},

issn = {2452-3216},

year  = {2022},

date = {2022-09-22},

journal = {Procedia Structural Integrity},

volume = {37},

pages = {314-320},

abstract = {Structural vulnerability assessment of heritage structures is a pivotal part of a risk mitigation strategy for preserving these valuable assets for the nations. For this purpose, developing digital twins has gained much attention lately to provide an accurate digital model for performing finite element (FE) analyses. Three-dimensional (3D) geometric documentation is the first step in developing the digital twin, and various equipment and methodologies have been developed to facilitate the procedure. Both aerial and terrestrial close-range photogrammetry can be combined with 3D laser scanning and geodetic methods for the accurate 3D geometric documentation. The data processing procedure in these cases mostly focuses on developing detailed, accurate 3D models that can be used for the FE modeling. The final 3D surface or volumes are produced mainly by combining the 3D point clouds obtained from the laser scanner and the photogrammetric methods. 3D FE models can be developed based on the geometries derived from the 3D models using FE software packages. As an alternative, developed 3D volumes provided in the previous step can be directly imported to some FE software packages. In this study, the challenges and strategies of each step are investigated by providing examples of surveyed heritage structures.},

note = {ICSI 2021 The 4th International Conference on Structural Integrity},

keywords = {3D geometric documentation, 3D laser scanner, Cultural heritage, Digital twins, Finite element model, Photogrammetry},

pubstate = {published},

tppubtype = {article}

}

@article{verykokou2022evaluation,

title = {Evaluation of 3D Modeling Workflows Using Dental CBCT Data for Periodontal Regenerative Treatment},

author = {Styliani Verykokou and Charalabos Ioannidis and Christos Angelopoulos},

url = {https://www.mdpi.com/2075-4426/12/9/1355},

doi = {10.3390/jpm12091355},

issn = {2075-4426},

year  = {2022},

date = {2022-08-23},

urldate = {2022-08-23},

journal = {J. Pers. Med.},

volume = {12},

number = {9},

pages = {1355},

publisher = {MDPI},

abstract = {The cone beam computed tomography (CBCT) technology is nowadays widely used in the field of dentistry and its use in the treatment of periodontal diseases has already been tackled in the international literature. At the same time, advanced segmentation methods have been introduced in state-of-the-art medical imaging software and well-established automated techniques for 3D mesh cleaning are available in 3D model editing software. However, except for the application of simple thresholding approaches for the purposes of 3D modeling of the oral cavity using CBCT data for dental applications, which does not yield accurate results, the research that has been conducted using more specialized semi-automated thresholding in dental CBCT images using existing software packages is limited. This article aims to fill the gap in the state-of-the-art research concerning the usage of CBCT data for 3D modeling of the hard tissues of the oral cavity of patients with periodontitis using existing software tools, for the needs of designing and printing 3D scaffolds for periodontal regeneration. In this context, segmentation and 3D modeling workflows using dental CBCT data that belong to a patient with periodontitis are evaluated, comparisons between the 3D models of the teeth and the alveolar bone generated through the experiments that yielded the most satisfactory results are made, and an optimal and efficient methodology for creating 3D models of teeth and alveolar bone, especially for being used as the basis for generating bioabsorbable 3D printed scaffolds of personalized treatment against periodontitis, is discussed.},

keywords = {3D modeling, CBCT, cone beam computed tomography, dental applications, periodontal treatment, periodontitis, scaffold, segmentation},

pubstate = {published},

tppubtype = {article}

}

@article{theodosopoulou2022fast,

title = {A Fast Data-Driven Tool for Flood Risk Assessment in Urban Areas},

author = {Zafeiria Theodosopoulou and Ioannis M Kourtis and Vasilis Bellos and Konstantinos Apostolopoulos and Chryssy Potsiou and Vassilios A Tsihrintzis},

url = {https://www.mdpi.com/2306-5338/9/8/147},

doi = {10.3390/hydrology9080147},

issn = {2306-5338},

year  = {2022},

date = {2022-08-16},

journal = {Hydrology},

volume = {9},

number = {8},

pages = {147},

publisher = {MDPI},

abstract = {Post-disaster flood risk assessment is extremely difficult owing to the great uncertainties involved in all parts of the assessment exercise, e.g., the uncertainty of hydrologic\textendashhydraulic models and depth\textendashdamage curves. In the present study, a robust and fast data-driven tool for residential flood risk assessment is introduced. The proposed tool can be used by scientists, practitioners and/or stakeholders as a first step for better understanding and quantifying flood risk in monetary terms. Another contribution of the present study is the fitting of an equation through depth\textendashdamage points provided by the Joint Research Center (JRC). The approach is based on hydrologic simulations for different return periods, employing a free and widely used software, HEC-HMS. Moreover, flood depths for the study area are estimated based on hydrodynamic simulations employing the HEC-RAS software and the Inverse Distance Weighting (IDW) interpolation method. Finally, flood risk, in monetary terms, is determined based on the flood depths derived by the coupling of hydrodynamic simulations and the IDW method, depth\textendashdamage curves reported in the literature, vulnerability of residential areas and the residential exposure derived by employing GIS tools. The proposed tool is applied in a highly urbanized and flood-prone area, Mandra city, in the Attica region of Greece. The results are maps of flood depths and flood risk maps for specific return periods. Overall, the results derived from the application of the proposed approach reveal that the tool can be highly effective for post-disaster flood risk management. However, it must be noted that additional information and post-disaster data are needed for the verification of the damages from floods. Additional information can result in better calibration, validation and overall performance of the proposed flood risk assessment tool.},

keywords = {depth\textendashdamage curves, event-based simulation, flood risk, hydrologic simulation, Mandra flood, post-disaster risk assessment},

pubstate = {published},

tppubtype = {article}

}

@article{potsiou2022technical,

title = {A Technical Tool for Urban Upgrading: An Application for Cultural Heritage Preservation and Planning for Affordable Housing},

author = {Chryssy Potsiou and Charalabos Ioannidis and Sofia Soile and Styliani Verykokou and Maria Gkeli and Maria Filippakopoulou},

url = {https://www.mdpi.com/2073-445X/11/8/1197},

doi = {10.3390/land11081197},

issn = {2073-445X},

year  = {2022},

date = {2022-07-29},

urldate = {2022-07-29},

journal = {Land},

volume = {11},

number = {8},

pages = {1197},

publisher = {MDPI},

abstract = {A technical tool to support projects for urban reforms and the implementation of current land policies is presented together with an example for its application in a project concerning the preservation of privately-owned residential buildings listed as “protected” cultural heritage (CH) constructions, urban planning and planning for affordable housing provision. The projects should be based on the voluntary participation of current property owners and an agreement signed between them and the private developer (team of professionals), so that the project will be self-financed through value capture measures to be decided by the state. The application presented here is based on the assumption that the state, by example, has set the rules for an increase in FAR in order to apply affordable housing policy and the preservation of listed CH residential private constructions. The state also provides the rules for identifying the target group of beneficiaries for affordable housing. Current property owners contribute the land, while the developer's team undertakes all project costs. New property units are shared accordingly with the developer, the current owners and the beneficiaries for affordable housing. No additional public funds for the “affordable housing” units or for expropriation of the protected CH buildings is required.},

keywords = {3D model, Affordable housing, Cultural heritage, land policy, urban planning, valuation},

pubstate = {published},

tppubtype = {article}

}

@article{andritsou2022bim,

title = {A BIM/IFC \textendash LADM SOLUTION ALIGNED TO THE GREEK LEGISLATION},

author = {D Andritsou and M Gkeli and S Soile and C Potsiou},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B4-2022/471/2022/},

doi = {10.5194/isprs-archives-XLIII-B4-2022-471-2022},

issn = {2194-9034},

year  = {2022},

date = {2022-06-02},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLIII-B4-2},

pages = {471--477},

publisher = {Copernicus GmbH},

abstract = {Abstract. The ongoing rapid urbanization has led to the emerge of several complex infrastructures distinguished by multi-dimensional and overlapping property rights. The option of integrating BIM data into LA, aligned with international standards and able to handle the three-dimensional (3D) aspect of cadastral objects utilizing contemporary technologies, may be of a great importance. The main objective of this paper is to investigate the potential integration of the Building Information Model (BIM) and the Industry Foundation Classes (IFC) standard, with the international standard of Land Administration Domain Model (LADM ISO 19152 2012), in order to provide a unified solution for the registration and visualization of 3D spatial and sematic information regarding the complex Rights, Restrictions and Responsibilities (RRR) in the new complex constructions. The proposed solution aims to exploit the available 2D plans for the generation of BIMs; and rely on international LADM's constructional guidelines to provide a standardized cadastral database harmonized with the national Greek cadastral and the legal framework and aligned with the current Greek building code. The proposed framework is tested for two multi-storey buildings. The first results are promising constituting an important tool, for the implementation of 3D cadastres.},

keywords = {3D cadastre, BIM, Greek Legislation, IFC, LADM, Volumetric Rights Restrictions Responsibilities},

pubstate = {published},

tppubtype = {article}

}

@article{boutsi2022pose,

title = {POSE ESTIMATION THROUGH MASK-R CNN AND VSLAM IN LARGE-SCALE OUTDOORS AUGMENTED REALITY},

author = {A-M Boutsi and N Bakalos and C Ioannidis},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/V-4-2022/197/2022/},

doi = {10.5194/isprs-annals-V-4-2022-197-2022},

issn = {2194-9050},

year  = {2022},

date = {2022-05-18},

journal = {ISPRS Ann. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {V-4-2022},

number = {4},

pages = {197--204},

abstract = {Abstract. Deep Learning (DL) ingrained into Mobile Augmented Reality (MAR) enables a new information-delivery paradigm. In the context of 6 DoF pose estimation, powerful DL networks could provide a direct solution for AR systems. However, their concurrent operation requires a significant number of computations per frame and yields to both misclassifications and localization errors. In this paper, a hybrid and lightweight solution on 3D tracking of arbitrary geometry for outdoor MAR scenarios is presented. The camera pose information obtained by ARCore SDK and vSLAM algorithm is combined with the semantic and geometric output of a CNN-object detector to validate and improve tracking performance in large-scale and uncontrolled outdoor environments. The methodology involves three main steps: i) training of the Mask-R CNN model to extract the class, bounding box and mask predictions, ii) real-time detection, segmentation and localization of the region of interest (ROI) in camera frames, and iii) computation of 2D-3D correspondences to enhance pose estimation of a 3D overlay. The dataset holds 30 images of the rock of St. Modestos \textendash Modi in Meteora, Greece in which the ROI is an area with characteristic geological features. The comparative evaluation between the prototype system and the original one, as well as with R-CNN and FAST-R CNN detectors demonstrates higher precision accuracy and stable visualization at half a kilometre distance, while tracking time has decreased at 42% during far-field AR session.},

keywords = {3D rendering, Augmented Reality, CNN, deep learning, image recognition, pose estimation},

pubstate = {published},

tppubtype = {article}

}

@article{liaskos2022,

title = {XR-RF Imaging Enabled by Software-Defined Metasurfaces and Machine Learning: Foundational Vision, Technologies and Challenges},

author = {Christos Liaskos and Ageliki Tsioliaridou and Konstantinos Georgopoulos and Ioannis Morianos and Sotiris Ioannidis and Iosif Salem and Dionyssios Manessis and Stefan Schmid and Dimitrios Tyrovolas and Sotiris A. Tegos and Prodromos-Vasileios Mekikis and Panagiotis D. Diamantoulakis and Alexandros Pitilakis and Nikolaos V. Kantartzis and George K. Karagiannidis and Anna C. Tasolamprou and Odysseas Tsilipakos and Maria Kafesaki and Ian F. Akyildiz and Andreas Pitsillides and Maria Pateraki and Michael Vakalellis and Ilias Spais},

doi = {10.1109/ACCESS.2022.3219871},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {IEEE Access},

volume = {10},

pages = {119841-119862},

keywords = {imaging, Metasurfaces, Radio frequency, Three-dimensional displays, Wireless communication, Wireless sensor networks, X reality},

pubstate = {published},

tppubtype = {article}

}

@article{Papoutsakis2022,

title = {Detection of Physical Strain and Fatigue in Industrial Environments Using Visual and Non-Visual Low-Cost Sensors},

author = {Konstantinos Papoutsakis and George Papadopoulos and Michail Maniadakis and Thodoris Papadopoulos and Manolis Lourakis and Maria Pateraki and Iraklis Varlamis},

editor = {Isabel L. Nunes},

url = {https://www.mdpi.com/2227-7080/10/2/42},

doi = {10.3390/technologies10020042},

issn = {2227-7080},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

booktitle = {Human Factors and Systems Interaction. AHFE (2022) International Conference},

journal = {Technologies},

volume = {10},

number = {2},

abstract = {The detection and prevention of workers’ body straining postures and other stressing conditions within the work environment, supports establishing occupational safety and promoting well being and sustainability at work. Developed methods towards this aim typically rely on combining highly ergonomic workplaces and expensive monitoring mechanisms including wearable devices. In this work, we demonstrate how the input from low-cost sensors, specifically, passive camera sensors installed in a real manufacturing workplace, and smartwatches used by the workers can provide useful feedback on the workers’ conditions and can yield key indicators for the prevention of work-related musculo-skeletal disorders (WMSD) and physical fatigue. To this end, we study the ability to assess the risk for physical strain of workers online during work activities based on the classification of ergonomically sub-optimal working postures using visual information, the correlation and fusion of these estimations with synchronous worker heart rate data, as well as the prediction of near-future heart rate using deep learning-based techniques. Moreover, a new multi-modal dataset of video and heart rate data captured in a real manufacturing workplace during car door assembly activities is introduced. The experimental results show the efficiency of the proposed approach that exceeds 70% of classification rate based on the F1 score measure using a set of over 300 annotated video clips of real line workers during work activities. In addition a time lagging correlation between the estimated ergonomic risks for physical strain and high heart rate was assessed using a larger dataset of synchronous visual and heart rate data sequences. The statistical analysis revealed that imposing increased strain to body parts will results in an increase to the heart rate after 100\textendash120 s. This finding is used to improve the short term forecasting of worker’s cardiovascular activity for the next 10 to 30 s by fusing the heart rate data with the estimated ergonomic risks for physical strain and ultimately to train better predictive models for worker fatigue.},

keywords = {Computer Vision, ergonomic risk, fatigue, heart rate, low cost sensors, occupational health, physical strain, predictive models, sensor fusion, WMSD, working postures},

pubstate = {published},

tppubtype = {article}

}

@article{Mallol2022,

title = {Outer Product-Based Fusion of Smartwatch Sensor Data for Human Activity Recognition},

author = {Adria Mallol-Ragolta and Anastasia Semertzidou and Maria Pateraki and Bj\"{o}rn Schuller},

url = {https://www.frontiersin.org/articles/10.3389/fcomp.2022.796866},

doi = {10.3389/fcomp.2022.796866},

issn = {2624-9898},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {Frontiers in Computer Science},

volume = {4},

abstract = {The advent of IoT devices in combination with Human Activity Recognition (HAR) technologies can contribute to battle with sedentariness by continuously monitoring the users' daily activities. With this information, autonomous systems could detect users' physical weaknesses and plan personalized training routines to improve them. This work investigates the multimodal fusion of smartwatch sensor data for HAR. Specifically, we exploit pedometer, heart rate, and accelerometer information to train unimodal and multimodal models for the task at hand. The models are trained end-to-end, and we compare the performance of dedicated Recurrent Neural Network-based (RNN) and Convolutional Neural Network-based (CNN) architectures to extract deep learnt representations from the input modalities. To fuse the embedded representations when training the multimodal models, we investigate a concatenation-based and an outer product-based approach. This work explores the harAGE dataset, a new dataset for HAR collected using a Garmin Vivoactive 3 device with more than 17 h of data. Our best models obtain an Unweighted Average Recall (UAR) of 95.6, 69.5, and 60.8% when tackling the task as a 2-class, 7-class, and 10-class classification problem, respectively. These performances are obtained using multimodal models that fuse the embedded representations extracted with dedicated CNN-based architectures from the pedometer, heart rate, and accelerometer modalities. The concatenation-based fusion scores the highest UAR in the 2-class classification problem, while the outer product-based fusion obtains the best performances in the 7-class and the 10-class classification problems.},

keywords = {artificial intelligence, Human Activity Recognition, multimodal fusion, smartwatch sensor data, ubiquitous computing},

pubstate = {published},

tppubtype = {article}

}

@article{MallolRagolta2022sustAGE1,

title = {sustAGE 1.0 \textendash First Prototype, Use Cases, and Usability Evaluation},

author = {Adria Mallol-Ragolta and Iraklis Varlamis and Maria Pateraki and Manolis I. A. Lourakis and Georgios Athanassiou and Michail Maniadakis and Konstantinos E. Papoutsakis and Thodoris Papadopoulos and Anastasia Semertzidou and Nicholas Cummins and Bj\"{o}rn Schuller and Ion-Anastasios Karolos and Christos Pikridas and Petros G. Patias and Spyros Vantolas and Leonidas Kallipolitis and Frank Werner and Antonio Ascolese and Vito Nitti},

url = {https://openaccess-api.cms-conferences.org/articles/download/978-1-7923-8989-4_58},

year  = {2022},

date = {2022-01-01},

urldate = {2022-01-01},

journal = {AHFE International},

abstract = {Worldwide demographics are changing; we are living longer and, in developed countries, the birth-rate is dropping. In this context and motivated by the challenge of sustainable ageing, this paper presents sustAGE, a multi-modal person-centred IoT platform, which integrates with the daily activities of ageing employees both at work and outside. The sensed information allows the system to assess the state of the users and context-related aspects with the aim to provide timely recommendations to support wellbeing, wellness, and productivity. Herein, we describe the use cases, outline the overall system architecture, and introduce the first prototype of the platform implemented up-to-date. Furthermore, the results from the usability evaluation conducted with real users who used the prototype for one month are presented},

keywords = {Ageing Workforce, artificial intelligence, IoT, Micro-moments, Occupational Safety and Health, Personalised Recommendations},

pubstate = {published},

tppubtype = {article}

}

@article{Gkeli2021,

title = {A BIM-IFC Technical Solution for 3D Crowdsourced Cadastral Surveys Based on LADM},

author = {Maria Gkeli and Chryssy Potsiou and Sofia Soile and Giorgos Vathiotis and Maria-Eleni Cravariti},

url = {https://www.mdpi.com/2673-4834/2/3/35},

doi = {10.3390/earth2030035},

issn = {2673-4834},

year  = {2021},

date = {2021-09-06},

urldate = {2021-01-01},

journal = {Earth},

volume = {2},

pages = {605-621},

abstract = {In most countries, three-dimensional (3D) property units are registered utilizing two-dimensional (2D) documentation and textual description. This approach has several limitations as it is unable to represent the actual extent of complicated 3D property units in space. As traditional procedures often lead to increased costs and long delays in 2D cadastral surveying, a fast, cost-effective, and reliable solution is needed to cope with the remaining global cadastral surveying needs. Crowdsourcing has claimed a critical role as a reliable methodology with huge potential regarding the realization of 2D and 3D cadastral registration in both an affordable and a timely manner. Many large modern constructions are now planned and constructed based on BIM technology all over the world. The utilization of 3D digital models, such as building information models (BIMs), and the establishment of a connection with the international standard of the Land Administration Domain Model (LADM) could be a solution for the rapid integration of these units into a 3D crowdsourced cadaster with a better representation of the cadastral boundaries of these units, a detailed visualization of complex infrastructures, and an enhancement in the interoperability between different parties and organizations. In this paper, the potential linkage between the BIM, the LADM, and crowdsourcing techniques is investigated in order to provide an effective technical solution for the integration of large new constructions into 3D crowdsourced cadastral surveys. The proposed framework is tested on a building block in Athens, Greece. The potential, perspectives, and reliability of such an implementation are assessed and discussed.},

keywords = {3D cadaster, BIM, Crowdsourcing, IFC, LADM},

pubstate = {published},

tppubtype = {article}

}

@article{gkeli2021bim,

title = {A BIM-IFC Technical Solution for 3D Crowdsourced Cadastral Surveys Based on LADM},

author = {Maria Gkeli and Chryssy Potsiou and Sofia Soile and Giorgos Vathiotis and Maria-Eleni Cravariti},

url = {https://www.mdpi.com/2673-4834/2/3/35},

doi = {10.3390/earth2030035},

issn = {2673-4834},

year  = {2021},

date = {2021-09-06},

urldate = {2021-09-06},

journal = {Earth},

volume = {2},

number = {3},

pages = {605--621},

publisher = {MDPI},

abstract = {In most countries, three-dimensional (3D) property units are registered utilizing two-dimensional (2D) documentation and textual description. This approach has several limitations as it is unable to represent the actual extent of complicated 3D property units in space. As traditional procedures often lead to increased costs and long delays in 2D cadastral surveying, a fast, cost-effective, and reliable solution is needed to cope with the remaining global cadastral surveying needs. Crowdsourcing has claimed a critical role as a reliable methodology with huge potential regarding the realization of 2D and 3D cadastral registration in both an affordable and a timely manner. Many large modern constructions are now planned and constructed based on BIM technology all over the world. The utilization of 3D digital models, such as building information models (BIMs), and the establishment of a connection with the international standard of the Land Administration Domain Model (LADM) could be a solution for the rapid integration of these units into a 3D crowdsourced cadaster with a better representation of the cadastral boundaries of these units, a detailed visualization of complex infrastructures, and an enhancement in the interoperability between different parties and organizations. In this paper, the potential linkage between the BIM, the LADM, and crowdsourcing techniques is investigated in order to provide an effective technical solution for the integration of large new constructions into 3D crowdsourced cadastral surveys. The proposed framework is tested on a building block in Athens, Greece. The potential, perspectives, and reliability of such an implementation are assessed and discussed.},

keywords = {3D cadaster, BIM, Crowdsourcing, IFC, LADM},

pubstate = {published},

tppubtype = {article}

}

@article{isprs-archives-XLVI-M-1-2021-739-2021,

title = {3D HOLISTIC DOCUMENTATION OF HERITAGE MONUMENTS IN RHODES},

author = {S Tapinaki and M Skamantzari and A Anastasiou and S Koutros and E Syrokou and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLVI-M-1-2021/739/2021/},

doi = {10.5194/isprs-archives-XLVI-M-1-2021-739-2021},

year  = {2021},

date = {2021-08-28},

urldate = {2021-08-28},

journal = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {XLVI-M-1-2021},

pages = {739--744},

keywords = {3D reconstruction, Cultural heritage, geometric documentation, Image based modelling, laser scanning},

pubstate = {published},

tppubtype = {article}

}

@article{isprs-archives-XLIII-B2-2021-583-2021,

title = {3D AND HYPERSPECTRAL DATA INTEGRATION FOR ASSESSING MATERIAL DEGRADATION IN MEDIEVAL MASONRY HERITAGE BUILDINGS},

author = {P Kolokoussis and M Skamantzari and S Tapinaki and V Karathanassi and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B2-2021/583/2021/},

doi = {10.5194/isprs-archives-XLIII-B2-2021-583-2021},

year  = {2021},

date = {2021-06-28},

urldate = {2021-06-28},

journal = {The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {XLIII-B2-2021},

pages = {583--590},

keywords = {3D reconstruction, Cultural heritage, Hyperspectral Images, Material Analysis, Photogrammetry},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2021,

title = {Learning from Synthetic Data: Enhancing Refraction Correction Accuracy for Airborne Image-Based Bathymetric Mapping of Shallow Coastal Waters},

author = {Panagiotis Agrafiotis and Konstantinos Karantzalos and Andreas Georgopoulos and Dimitrios Skarlatos},

url = {https://link.springer.com/10.1007/s41064-021-00144-1},

doi = {10.1007/s41064-021-00144-1},

issn = {2512-2789},

year  = {2021},

date = {2021-05-01},

journal = {PFG \textendash J. Photogramm. Remote Sens. Geoinf. Sci.},

pages = {1--19},

publisher = {Springer},

abstract = {The increasing need for accurate bathymetric mapping is essential for a plethora of offshore activities. Even though aerial image datasets through Structure from Motion (SfM) and Multi-View Stereo (MVS) techniques can provide a low-cost alternative compared to LiDAR and SONAR, offering additionally, important visual information, water refraction poses significant obstacles in delivering accurate bathymetry. In this article, the generation of manned and unmanned airborne synthetic datasets of dry and water covered areas is presented. These data are used to train models for correcting the geometric effects of refraction on real-world image-based point clouds and aerial images. Based on a thorough evaluation, important improvements are presented, indicating the increased accuracy and the reduced noise in the point clouds of the derived bathymetric products, meeting also the International Hydrographic Organization's (IHO) standards.},

keywords = {Aerospace Technology and Astronautics, Astronomy, Computer Imaging, Geographical Information Systems/Cartography, Image and Speech Processing, Observations and Techniques, Pattern Recognition and Graphics, Remote Sensing/Photogrammetry, Signal, Vision},

pubstate = {published},

tppubtype = {article}

}

@article{Dolapsaki2021,

title = {Edge Detection in 3D Point Clouds Using Digital Images},

author = {Maria Melina Dolapsaki and Andreas Georgopoulos},

url = {https://doi.org/10.3390/ijgi10040229},

doi = {10.3390/ijgi10040229},

year  = {2021},

date = {2021-04-01},

journal = {ISPRS Int. J. Geo-Information},

volume = {10},

number = {4},

pages = {229},

publisher = {MDPI AG},

abstract = {This paper presents an effective and semi-automated method for detecting 3D edges in 3D point clouds with the help of high-resolution digital images. The effort aims to contribute towards addressing the unsolved problem of automated production of vector drawings from 3D point clouds of cultural heritage objects. Edges are the simplest primitives to detect in an unorganized point cloud and an algorithm was developed to perform this task. The provided edges are defined and measured on 2D digital images of known orientation, and the algorithm determines the plane defined by the edge on the image and its perspective center. This is accomplished by applying suitable transformations to the image coordinates of the edge points based on the Analytical Geometry relationships and properties of planes in 3D space. This plane inevitably contains the 3D points of the edge in the point cloud. The algorithm then detects and isolates those points which define the edge in the world system. Finally, the goal is to reliably locate the points that describe the desired edge in their true position in the geodetic space, using several constraints. The algorithm is firstly investigated theoretically for its efficiency using simulation data and then assessed under real conditions and under different image orientations and lengths of the edge on the image. The results are presented and evaluated.},

keywords = {Cultural heritage, Edge detection, large scales, Point clouds},

pubstate = {published},

tppubtype = {article}

}

@article{rs13061053,

title = {Semantically Derived Geometric Constraints for MVS Reconstruction of Textureless Areas},

author = {Elisavet Konstantina Stathopoulou and Roberto Battisti and Dan Cernea and Fabio Remondino and Andreas Georgopoulos},

url = {https://www.mdpi.com/2072-4292/13/6/1053},

doi = {10.3390/rs13061053},

issn = {2072-4292},

year  = {2021},

date = {2021-03-10},

urldate = {2021-03-10},

journal = {Remote Sensing},

volume = {13},

number = {6},

abstract = {Conventional multi-view stereo (MVS) approaches based on photo-consistency measures are generally robust, yet often fail in calculating valid depth pixel estimates in low textured areas of the scene. In this study, a novel approach is proposed to tackle this challenge by leveraging semantic priors into a PatchMatch-based MVS in order to increase confidence and support depth and normal map estimation. Semantic class labels on image pixels are used to impose class-specific geometric constraints during multiview stereo, optimising the depth estimation on weakly supported, textureless areas, commonly present in urban scenarios of building facades, indoor scenes, or aerial datasets. Detecting dominant shapes, e.g., planes, with RANSAC, an adjusted cost function is introduced that combines and weighs both photometric and semantic scores propagating, thus, more accurate depth estimates. Being adaptive, it fills in apparent information gaps and smoothing local roughness in problematic regions while at the same time preserves important details. Experiments on benchmark and custom datasets demonstrate the effectiveness of the presented approach.},

keywords = {3D reconstruction, dense point cloud, depth estimation, multi view stereo (MVS), PatchMatch, Plane detection, RANSAC, semantic segmentation},

pubstate = {published},

tppubtype = {article}

}

@article{apostolopoulos2022consideration,

title = {Consideration on how to introduce gamification tools to enhance citizen engagement in crowdsourced cadastral surveys},

author = {Konstantinos Apostolopoulos and Chryssy Potsiou},

url = {https://www.tandfonline.com/doi/full/10.1080/00396265.2021.1888027},

doi = {10.1080/00396265.2021.1888027},

issn = {0039-6265},

year  = {2021},

date = {2021-02-23},

urldate = {2021-02-23},

journal = {Surv. Rev.},

volume = {54},

number = {383},

pages = {142--152},

publisher = {Taylor \& Francis},

abstract = {The major objective of this research is to investigate the progress of citizen participation in cadastral surveying and to consider ways on how to introduce gamification tools for further improvement. A brief literature review is presented in the areas of the Sustainable Development Agenda 2030 related to land administration and citizen engagement, e-government and citizen participation and gamification tools for citizen engagement. This paper, also, includes an investigation of the progress in introducing volunteerism and citizen participation to the Hellenic Cadastre. A case study is held by a group of volunteers in order to assess the developed tools designed either by the private sector or by the cadastral agency.},

keywords = {Cadastral surveying, Citizen participation, Crowdsourcing, Gamification, Land administration, VGI},

pubstate = {published},

tppubtype = {article}

}

@article{isprs-annals-V-2-2021-113-2021,

title = {A WEB-BASED PLATFORM FOR MANAGEMENT AND VISUALIZATION OF GEOMETRIC DOCUMENTATION PRODUCTS OF CULTURAL HERITAGE SITES},

author = {C Ioannidis and I Tallis and I Pastos and A -M Boutsi and S Verykokou and S Soile and P Tokmakidis and K Tokmakidis},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/V-2-2021/113/2021/},

doi = {10.5194/isprs-annals-V-2-2021-113-2021},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {V-2-2021},

pages = {113--120},

keywords = {3D viewer, Cultural Heritage visualization, multi-users, RDBMS, spatial data, web application platform},

pubstate = {published},

tppubtype = {article}

}

@article{isprs-annals-VIII-M-1-2021-57-2021,

title = {Α PATTERN-BASED AUGMENTED REALITY APPLICATION FOR THE DISSEMINATION OF CULTURAL HERITAGE},

author = {A -M Boutsi and S Verykokou and S Soile and C Ioannidis},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/VIII-M-1-2021/57/2021/},

doi = {10.5194/isprs-annals-VIII-M-1-2021-57-2021},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences},

volume = {VIII-M-1-2021},

pages = {57--63},

keywords = {3D modelling, Augmented Reality, Computer Vision, Cultural heritage, mobile app, Photogrammetry},

pubstate = {published},

tppubtype = {article}

}

@article{app11188750,

title = {Mobile Augmented Reality for Low-End Devices Based on Planar Surface Recognition and Optimized Vertex Data Rendering},

author = {Styliani Verykokou and Argyro-Maria Boutsi and Charalabos Ioannidis},

url = {https://www.mdpi.com/2076-3417/11/18/8750},

doi = {10.3390/app11188750},

issn = {2076-3417},

year  = {2021},

date = {2021-01-01},

urldate = {2021-01-01},

journal = {Applied Sciences},

volume = {11},

number = {18},

abstract = {Mobile Augmented Reality (MAR) is designed to keep pace with high-end mobile computing and their powerful sensors. This evolution excludes users with low-end devices and network constraints. This article presents ModAR, a hybrid Android prototype that expands the MAR experience to the aforementioned target group. It combines feature-based image matching and pose estimation with fast rendering of 3D textured models. Planar objects of the real environment are used as pattern images for overlaying users’ meshes or the app’s default ones. Since ModAR is based on the OpenCV C++ library at Android NDK and OpenGL ES 2.0 graphics API, there are no dependencies on additional software, operating system version or model-specific hardware. The developed 3D graphics engine implements optimized vertex-data rendering with a combination of data grouping, synchronization, sub-texture compression and instancing for limited CPU/GPU resources and a single-threaded approach. It achieves up to 3× speed-up compared to standard index rendering, and AR overlay of a 50 K vertices 3D model in less than 30 s. Several deployment scenarios on pose estimation demonstrate that the oriented FAST detector with an upper threshold of features per frame combined with the ORB descriptor yield best results in terms of robustness and efficiency, achieving a 90% reduction of image matching time compared to the time required by the AGAST detector and the BRISK descriptor, corresponding to pattern recognition accuracy of above 90% for a wide range of scale changes, regardless of any in-plane rotations and partial occlusions of the pattern.},

keywords = {3D rendering, BRISK, camera pose estimation, geometric instancing, mobile augmented reality, OpenCV, OpenGL ES, ORB, pattern recognition, vertex-based rendering},

pubstate = {published},

tppubtype = {article}

}

@article{Apostolopoulos2021,

title = {Consideration on how to introduce gamification tools to enhance citizen engagement in crowdsourced cadastral surveys},

author = {Konstantinos Apostolopoulos and Chryssy Potsiou},

url = {https://doi.org/10.1080/00396265.2021.1888027},

doi = {10.1080/00396265.2021.1888027},

year  = {2021},

date = {2021-01-01},

journal = {Survey Review},

volume = {0},

pages = {1-11},

publisher = {Taylor \& Francis},

abstract = {The major objective of this research is to investigate the progress of citizen participation in cadastral surveying and to consider ways on how to introduce gamification tools for further improvement. A brief literature review is presented in the areas of the Sustainable Development Agenda 2030 related to land administration and citizen engagement, e-government and citizen participation and gamification tools for citizen engagement. This paper, also, includes an investigation of the progress in introducing volunteerism and citizen participation to the Hellenic Cadastre. A case study is held by a group of volunteers in order to assess the developed tools designed either by the private sector or by the cadastral agency.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Bakogiannis2021,

title = {Crowdsourced Geospatial Infrastructure for Coastal Management and Planning for Emerging Post COVID-19 Tourism Demand},

author = {Efthimios Bakogiannis and Chryssy Potsiou and Konstantinos Apostolopoulos and Charalampos Kyriakidis},

url = {https://www.mdpi.com/2673-5768/2/2/16},

doi = {10.3390/tourhosp2020016},

issn = {2673-5768},

year  = {2021},

date = {2021-01-01},

journal = {Tourism and Hospitality},

volume = {2},

pages = {261-276},

publisher = {CRC Press},

abstract = {
In recent years, the use of crowdsourcing has positively transformed the way geographic information is collected, stored and analyzed. Many countries have promoted and funded research into the potential of using crowdsourcing in various fields of governance. This paper focuses on developing a methodology for fast, low-cost and reliable coastal management for touristic purposes in Greece. In particular, a group of a professional surveyor have developed the methodology and trained two volunteers to collect a variety of data points of interest about a public coastal zone, such as the area size of free and unused public space, rocky areas, parking spaces (organized or not), land use types, build up and green areas, municipal lighting, pedestrian crossing points, beach umbrellas, path routes, street furniture, etc. A pilot case study was compiled for a part of the Athenian Riviera to check the methodology. Derived conclusions point out that the developed methodology may be successfully used for managing the 16,000 km length of the coastal zone of Greece for touristic purposes. Considerations for further improvements to the methodology are given.
},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Verykokou2020,

title = {Exterior orientation estimation of oblique aerial images using SfM-based robust bundle adjustment},

author = {Styliani Verykokou and Charalabos Ioannidis},

url = {https://www.tandfonline.com/action/journalInformation?journalCode=tres20 https://www.tandfonline.com/doi/full/10.1080/01431161.2020.1755737},

doi = {10.1080/01431161.2020.1755737},

issn = {0143-1161},

year  = {2020},

date = {2020-09-01},

journal = {Int. J. Remote Sens.},

volume = {41},

number = {18},

pages = {7233--7270},

abstract = {In this article, a structure from motion (SfM) framework for oblique aerial images of man-made environments is proposed, covering the issues of determining overlapping images, feature extraction, image matching, rejection of erroneous correspondences, feature tracking, automatic transfer of ground control points (GCPs), and bundle block adjustment. One of the challenges that it is intended to solve is the reduction of the required manual work concerning the measurement of GCPs, in order to increase the degree of automation of the exterior orientation estimation process, through the usage of geometric constraints automatically imposed. Yet another challenge is the difficulty in matching correctly feature points among multiple oblique views that depict scenes with repetitive patterns and homogeneous textures. The proposed algorithm solves this by eliminating all erroneous tie points through the combination of multiple checks and geometric constraints imposed during the image matching procedure and a robust iterative bundle adjustment framework. The proposed SfM methodology is applied in different configurations of oblique images under non-ideal aerial triangulation scenarios characterized by lack of well-distributed GCPs as well as minimum manual image measurements. The results are analysed, focusing on the improvement of the accuracy of the exterior orientation parameters thanks to the proposed robust out-lier removal technique as well as on the impact of the proposed scale-based weighting strategy for bundle adjustment of oblique images on the exterior orientation results. The proposed SfM framework proves to be a good alternative solution to existing commercial SfM methods. ARTICLE HISTORY},

keywords = {aerial triangulation, exterior orientation, oblique aerial images, Photogrammetry, structure from motion},

pubstate = {published},

tppubtype = {article}

}

@article{Ioannidis2020a,

title = {MULTITHREADED RENDERING FOR CROSS-PLATFORM 3D VISUALIZATION BASED ON VULKAN API},

author = {Charalabos Ioannidis and Argyro-Maria Boutsi},

url = {https://doi.org/10.5194/isprs-archives-XLIV-4-W1-2020-57-2020 https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIV-4-W1-2020/57/2020/},

doi = {10.5194/isprs-archives-XLIV-4-W1-2020-57-2020},

issn = {2194-9034},

year  = {2020},

date = {2020-09-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLIV-4/W1-},

pages = {57--62},

abstract = {Abstract. The visualization of large-sized 3D geospatial models is a graphics intensive task. With ever increasing size and complexity, more computing resources are needed to attain speed and visual quality. Exploiting the parallelism and the multi-core performance of the Graphics Processing Unit (GPU), a cross-platform 3D viewer is developed based on the Vulkan API and modern C++. The proposed prototype aims at the visualization of a textured 3D mesh of the Cultural Heritage by enabling a multi-threaded rendering pipeline. The rendering workload is distributed across many CPU threads by recording multiple command buffers in parallel and coordinating the host and the GPU rendering phases. To ensure efficient multi-threading behavior and a minimum overhead, synchronization primitives are exploiting for ordering the execution of queues and command buffers. Furthermore, push-constants are used to send uniform data to the GPU and render passes to adapt to the tile-based rendering of the mobile devices. The proposed methodology and technical solution are designed, implemented and tested for Windows, MacOS and Android on Vulkan-compatible GPU hardware by compiling the same codebase. The benchmarking on multiple hardware, architectures and platforms explores the performance improvement for the different approaches compared to one-thread and showcase the potential of the 3D viewer to handle large datasets at no expense of visual quality and geometric fidelity in the absence of high-end technological resources.},

keywords = {3D visualization, Computer graphics, geospatial data, graphics API, Vulkan},

pubstate = {published},

tppubtype = {article}

}

@article{Voulodimos2020,

title = {NOISE-TOLERANT HYPERSPECTRAL IMAGE CLASSIFICATION USING DISCRETE COSINE TRANSFORM AND CONVOLUTIONAL NEURAL NETWORKS},

author = {Athanasios Voulodimos and K Fokeas and Nikolaos Doulamis and Anastasios Doulamis and K Makantasis},

url = {https://doi.org/10.5194/isprs-archives-XLIII-B2-2020-1281-2020 https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B2-2020/1281/2020/},

doi = {10.5194/isprs-archives-XLIII-B2-2020-1281-2020},

issn = {2194-9034},

year  = {2020},

date = {2020-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLIII-B2-2},

pages = {1281--1287},

abstract = {Abstract. Hyperspectral image classification has drawn significant attention in the recent years driven by the increasing abundance of sensor-generated hyper- and multi-spectral data, combined with the rapid advancements in the field of machine learning. A vast range of techniques, especially involving deep learning models, have been proposed attaining high levels of classification accuracy. However, many of these approaches significantly deteriorate in performance in the presence of noise in the hyperspectral data. In this paper, we propose a new model that effectively addresses the challenge of noise residing in hyperspectral images. The proposed model, which will be called DCT-CNN, combines the representational power of Convolutional Neural Networks with the noise elimination capabilities introduced by frequency-domain filtering enabled through the Discrete Cosine Transform. In particular, the proposed method entails the transformation of pixel macroblocks to the frequency domain and the discarding of information that corresponds to the higher frequencies in every patch, in which pixel information of abrupt changes and noise often resides. Experiment results in Indian Pines, Salinas and Pavia University datasets indicate that the proposed DCT-CNN constitutes a promising new model for accurate hyperspectral image classification offering robustness to different types of noise, such as Gaussian and salt and pepper noise.},

keywords = {Convolutional Neural Networks, deep learning, Discrete Cosine Transform, Hyperspectral image classification, noise tolerance, robustness to noise},

pubstate = {published},

tppubtype = {article}

}

@article{isprs-archives-XLIII-B2-2020-55-2020,

title = {POSE ESTIMATION OF A MOVING CAMERA WITH LOW-COST, MULTI-GNSS DEVICES},

author = {M Lourakis and M Pateraki and I -A Karolos and C Pikridas and P Patias},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B2-2020/55/2020/},

doi = {10.5194/isprs-archives-XLIII-B2-2020-55-2020},

issn = {2194-9034},

year  = {2020},

date = {2020-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLIII-B2-2},

pages = {55--62},

abstract = {Abstract. Without additional prior information, the pose of a camera estimated with computer vision techniques is expressed in a local coordinate frame attached to the camera's initial location. Albeit sufficient in many cases, such an arbitrary representation is not convenient for employment in certain applications and has to be transformed to a coordinate system external to the camera before further use. Assuming a camera that is firmly mounted on a moving platform, this paper describes a method for continuously tracking the pose of that camera in a projected coordinate system. By combining exterior orientation from a known target with incremental pose changes inferred from accurate multi-GNSS positioning, the full 6 DoF pose of the camera is updated with low processing overhead and without requiring the continuous visual tracking of ground control points. Experimental results of applying the proposed method to a moving vehicle and a mobile port crane are reported, demonstrating its efficacy and potential.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Ioannidis2020b,

title = {A MULTI-PURPOSE CULTURAL HERITAGE DATA PLATFORM FOR 4D VISUALIZATION AND INTERACTIVE INFORMATION SERVICES},

author = {Charalabos Ioannidis and Styliani Verykokou and Sofia Soile and Argyro-Maria Boutsi},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLIII-B4-2020/583/2020/},

doi = {10.5194/isprs-archives-XLIII-B4-2020-583-2020},

issn = {2194-9034},

year  = {2020},

date = {2020-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLIII-B4-2},

number = {B4},

pages = {583--590},

publisher = {Copernicus GmbH},

abstract = {Abstract. The already arduous task of collecting, processing and managing heterogeneous cultural heritage data is getting more intense in terms of indexing, interaction and dissemination. This paper presents the creation of a 4D web-based platform as a centralized data hub, moving beyond advanced photogrammetric techniques for 3D capture and multi-dimensional documentation. Precise metric data, generated by a combination of image-based, range and surveying techniques, are spatially, logically and temporally correlated with cultural and historical resources, in order to form a critical knowledge base for multiple purposes and user types. Unlike conventional information systems, the presented platform, which adopts a relational database model, has the following front-end functionalities: (i) visualization of high-resolution 3D models based on distance dependent Level of Detail (LoD) techniques; (ii) web Augmented Reality; and (iii) interactive access and retrieval services. Information deduced from the developed services is tailored to different target audiences: scientific community, private sector, public sector and general public. The case study site is the UNESCO world heritage site of Meteora, Greece, and particularly, two inaccessible huge rocks, the rock of St. Modestos, known as Modi, and the Alyssos rock.},

keywords = {4D modelling, Cultural heritage, Documentation, geospatial data, visualization},

pubstate = {published},

tppubtype = {article}

}

@article{Katsamenis2020,

title = {Pixel-level Corrosion Detection on Metal Constructions by Fusion of Deep Learning Semantic and Contour Segmentation},

author = {Iason Katsamenis and Eftychios Protopapadakis and Anastasios Doulamis and Nikolaos Doulamis and Athanasios Voulodimos},

url = {http://arxiv.org/abs/2008.05204},

year  = {2020},

date = {2020-08-01},

abstract = {Corrosion detection on metal constructions is a major challenge in civil engineering for quick, safe and effective inspection. Existing image analysis approaches tend to place bounding boxes around the defected region which is not adequate both for structural analysis and pre-fabrication, an innovative construction concept which reduces maintenance cost, time and improves safety. In this paper, we apply three semantic segmentation-oriented deep learning models (FCN, U-Net and Mask R-CNN) for corrosion detection, which perform better in terms of accuracy and time and require a smaller number of annotated samples compared to other deep models, e.g. CNN. However, the final images derived are still not sufficiently accurate for structural analysis and pre-fabrication. Thus, we adopt a novel data projection scheme that fuses the results of color segmentation, yielding accurate but over-segmented contours of a region, with a processed area of the deep masks, resulting in high-confidence corroded pixels.},

keywords = {boundary refinement, corrosion detection, deep learning, Index Terms-Semantic segmentation},

pubstate = {published},

tppubtype = {article}

}

@article{Tentoma2020,

title = {COMPARATIVE INVESTIGATION OF THE 3D REPRESENTATIONS OF THE HOLY AEDICULE OF THE TOMB OF CHRIST},

author = {Nefeli Tentoma and Andreas Georgopoulos and Grazia Tucci},

url = {https://doi.org/10.4995/Arqueologica9.2021.12153},

doi = {10.4995/Arqueologica9.2021.12153},

year  = {2020},

date = {2020-04-01},

journal = {Arqueol. 2.0 - 9th Int. Congr. 3rd GEORES - GEOmatics Preserv.},

abstract = {The significance of preservation of cultural heritage is undeniable, which is why both their geometric documentation and the creation of their digital "twins", i.e., reconstructions and replicas at any scale, are essential procedures. A special category of cultural heritage is sacred sites which combine historical, spiritual and religious values. The most sacred monument of Christianity is the Holy Aedicule covering the Tomb of Christ in the Church of the Holy Sepulchre in Jerusalem. This paper aims to investigate and compare the various three-dimensional representations of the Holy Aedicule of the Tomb of Christ, which exist both in physical and in digital form. Initially, the main structural phases of the Aedicule are presented, including its destructions and restorations. Moreover, the different categories of the three-dimensional representations of the monument are defined. With reference to the replicas, both the reasons of their construction and their list in the form of a dataset table are presented. More specifically, in the context of this research, the three-dimensional representations of the Aedicule are divided into two major categories: the replicas constructed worldwide and the geometric documentations of the monument's condition through the years. Regarding the replicas, a list of the discovered representations is created, and this database is visualized and depicted in an online web map along with essential information with the use of an open-source Geographic Information System (GIS). Based on this visualization an online web map has been created. Furthermore, the previous geometric documentations and surveys of the Holy Aedicule of the Tomb of Christ are presented. A comparison is conducted between the 3D models of the Aedicule, which were created by the University of Florence in 2007-8 and the National Technical University of Athens in 2015-17. The impact of the Holy Aedicule across the world is examined through statistics based on the type, date of construction and location of the replicas. The possible deformations of the monument's structure are detected from the assessment of the results from both the processing and the comparison of the 3D models. In conclusion, future works are suggested focusing on the discovery of the total number of replicas worldwide and the monitoring of the condition of the Aedicule.},

keywords = {3D reconstruction, Cultural heritage, digital photogrammetry, geometric documentation, online webmap, three-dimensional representations},

pubstate = {published},

tppubtype = {article}

}

@article{Mourafetis2020,

title = {IT services and crowdsourcing in support of the hellenic cadastre: Advanced citizen participation and crowdsourcing in the official property registration process},

author = {George Mourafetis and Chryssy Potsiou},

url = {www.mdpi.com/journal/ijgi},

doi = {10.3390/ijgi9040190},

issn = {22209964},

year  = {2020},

date = {2020-03-01},

journal = {ISPRS Int. J. Geo-Information},

volume = {9},

number = {4},

pages = {190},

publisher = {MDPI AG},

abstract = {Greece is one of the few European countries that has not yet a fully operating Cadastre at national coverage. Cadastral surveying and property registration have been completed only for about 8% of the Greek territory, which includes about 18% of the total property rights. At the remaining areas, cadastral surveying and property registration is still under development and is expected to be completed by the end of 2021. The cadastral survey is a participatory procedure in which property right holders, or their representatives, are expected to declare the land parcels on which they have property rights and submit all documents that prove these rights. The time frame available for the declaration is 3 months, which is specific for each municipality. Right holders are now enabled to provide both spatial and descriptive information, regarding their properties and property rights, without the need of a professional. That includes the parcel's boundary lines along with the legal documents required to validate the declaration. Each right holder, or a representative, has the option to submit a declaration over the internet through a web application without the need of a professional. Within the frame of a PhD research, several concerns were addressed such as usability, security, and scalability in order for the outcome to support its scope while respecting binding constrains. As a result, two web applications have been created to officially support the Hellenic Cadaster property rights declaration process. The suggested approach was considered a big success in terms of both public acceptance and usability as shown from the statistics collected during the first eight months of its formal operation.},

keywords = {Cadaster, Crowdsourcing, Land administration, Mobile services, VGI},

pubstate = {published},

tppubtype = {article}

}

@article{Potsiou2020,

title = {Reliable 2D Crowdsourced Cadastral Surveys: Case Studies from Greece and Romania},

author = {Chryssy Potsiou and Cornel Paunescu and Charalabos Ioannidis and Konstantinos Apostolopoulos and Florin Nache},

url = {www.mdpi.com/journal/ijgi https://www.mdpi.com/2220-9964/9/2/89},

doi = {10.3390/ijgi9020089},

issn = {2220-9964},

year  = {2020},

date = {2020-02-01},

journal = {ISPRS Int. J. Geo-Information},

volume = {9},

number = {2},

pages = {89},

abstract = {This paper is part of a doctoral dissertation (PhD) research that investigates the development of a procedure for reliable 2D crowdsourced cadastral surveying introducing the use of new Information Technology IT tools and increased citizen participation, supported by m-services. For the development of this procedure, the formal cadastral procedure applied currently in two Europeans countries, Greece and Romania, for their modern nation-wide projects is firstly investigated. The first part of this paper briefly investigates the current stage of progress of those projects in both countries, as well as the specifications and procedures applied for the cadastral surveys, and assesses the level of participation of the right holders and the efficiency of the current procedures. Then, a proposal for a crowdsourced general procedure with increased participation of the right holders in the initial cadastral data collection phase is designed that it may be of value either for the planners of those two projects to improve their projects towards a more fit-for-purpose approach and successfully meet the deadlines timely, or for researchers and planners of other projects with similar nation-wide approaches which also require accurate, assured and authoritative end products. For the assessment of the applicability of the proposal, three case studies are held and tested in urban, rural and suburban areas in both countries, using both a commercial application and an open source one. These crowdsourced surveys are compared to the formal cadastral surveys that have been compiled by cadastral professionals in both countries and the achieved results are assessed and judged as satisfactory in terms of geometric accuracies and the avoidance of gross errors in the location of the parcels. A proposal for future research in order to further improve the proposed procedure is discussed.},

keywords = {Cadastre, Crowdsourcing, Land administration, opensource},

pubstate = {published},

tppubtype = {article}

}

@article{Tsilimantou2020,

title = {GIS and BIM as Integrated Digital Environments for Modeling and Monitoring of Historic Buildings},

author = {Elisavet Tsilimantou and Ekaterini T Delegou and Ioannis A Nikitakos and Charalabos Ioannidis and Antonia Moropoulou},

url = {www.mdpi.com/journal/applsci https://www.mdpi.com/2076-3417/10/3/1078},

doi = {10.3390/app10031078},

issn = {2076-3417},

year  = {2020},

date = {2020-02-01},

journal = {Appl. Sci.},

volume = {10},

number = {3},

pages = {1078},

abstract = {Multidisciplinary data integration within an information system is considered a key point for rehabilitation projects. Information regarding the state of preservation and/or decision making, for sustainable restoration is prerequisite. In addition, achieving structural integrity of a historic building, especially one that has undergone many construction phases and restoration interventions, is a very elaborate task and should, therefore, involve the study of multidisciplinary information regarding historical, architectural, building material and geometric data. In this paper the elaboration of such data within 2D and 3D information systems is described. Through the process described herein, a methodology, including the acquisition, classification and management of various multisensory data, is displayed and applied within a geographic information system (GIS). Moreover, the multidisciplinary documentation process, aggregated with the surveying products, generates 3D heritage building information modeling (HBIM), including information regarding construction phases, pathology and current state of preservation of a building. The assessment of the applied methodology is performed concluding in a qualitative and a quantitative manner, in both 2D and 3D environments, providing information to facilitate the structural assessment of a historic building. Thus, in this work, the described methodology is presented, combining the multidisciplinary data with the development of GIS thematic maps and an HBIM. Representative results of the suggested methodology applied on the historic building of Villa Klonaridi, Athens, Greece are displayed.},

keywords = {building materials, cracks, Cultural heritage, Decay, geometric documentation, GIS thematic mapping, HBIM, monitoring, multidisciplinary documentation, structural integrity},

pubstate = {published},

tppubtype = {article}

}

@article{Antoniou2020,

title = {A deep learning method to accelerate the disaster response process},

author = {Vyron Antoniou and Chryssy Potsiou},

url = {https://www.unisdr.org/},

doi = {10.3390/rs12030544},

issn = {20724292},

year  = {2020},

date = {2020-02-01},

journal = {Remote Sens.},

volume = {12},

number = {3},

pages = {544},

publisher = {MDPI AG},

abstract = {This paper presents an end-to-end methodology that can be used in the disaster response process. The core element of the proposed method is a deep learning process which enables a helicopter landing site analysis through the identification of soccer fields. The method trains a deep learning autoencoder with the help of volunteered geographic information and satellite images. The process is mostly automated, it was developed to be applied in a time-and resource-constrained environment and keeps the human factor in the loop in order to control the final decisions. We show that through this process the cognitive load (CL) for an expert image analyst will be reduced by 70%, while the process will successfully identify 85.6% of the potential landing sites. We conclude that the suggested methodology can be used as part of a disaster response process.},

keywords = {artificial intelligence, deep learning, Deep learning autoencoder, Disaster response management, Helicopter landing site analysis, Machine Learning, Object detection, Satellite imagery, Volunteered geographic information},

pubstate = {published},

tppubtype = {article}

}

@article{Bakogiannis2020,

title = {How to adopt BIM in the building construction sector across greece?},

author = {Efthimios Bakogiannis and Kalliopi Papadaki and Charalampos Kyriakidis and Chryssy Potsiou},

url = {www.mdpi.com/journal/applsci},

doi = {10.3390/app10041371},

issn = {20763417},

year  = {2020},

date = {2020-02-01},

journal = {Appl. Sci.},

volume = {10},

number = {4},

pages = {1371},

publisher = {MDPI AG},

abstract = {The construction sector is of strategic importance for the European Commission. This is the reason why there is a special interest in the development of this sector which is attempting to transform into a more sustainable one in order to face various challenges. In this context, European Directive 2014/24/EU brings to the foreground of the European institutional framework the term building information modelling (BIM), that it is widely used in many countries across Europe. In Greece, the situation seems to be different, not only because it has not been applied in practice but also because of some special features of the way the construction sector functions. This paper presents the BIM use-level in Greece and the way with which it could be better integrated in the construction sector. Through this review we make a brief assessment of the strategy developed in order for the BIM to be integrated in Greek building procedures. Furthermore, we focus on specific issues, like the extended informal housing phenomenon, and on factors that cannot easily be standardized that create problems in BIM use. Finally, through an initial market analysis we underline the role of academic institutions for integrating BIM across Greece.},

keywords = {BIM, Greece, Policies, Public sector, Task group},

pubstate = {published},

tppubtype = {article}

}

@article{Stampouloglou2020,

title = {Archaeological anastylosis of two Macedonian tombs in a 3D virtual environment},

author = {Maria Stampouloglou and Olympia Toska and Sevasti Tapinaki and Georgia Kontogianni and Margarita Skamantzari and Andreas Georgopoulos},

url = {https://doi.org/10.4995/var.2020.11877 https://polipapers.upv.es/index.php/var/article/view/11877},

doi = {10.4995/var.2020.11877},

issn = {1989-9947},

year  = {2020},

date = {2020-01-01},

journal = {Virtual Archaeol. Rev.},

volume = {11},

number = {22},

pages = {26},

publisher = {Universitat Politecnica de Valencia},

abstract = {Archaeological restoration of monuments is a practice requiring extreme caution and thorough study. Archaeologists and conservation experts are very reluctant to proceed to restoration and indeed to reconstruction actions without detailed consultation and thought. Nowadays, anastylosis executed on the real object is practically prohibited. Contemporary technologies have provided archaeologists and other conservation experts with the tools to embark on virtual restorations or anastyloses, thus testing various alternatives without physical intervention on the monument itself. In this way, the values of the monuments are respected according to international conventions. In this paper, two such examples of virtual archaeological anastyloses of two important Macedonian tombs in northern Greece are presented. The anastyloses were performed on three-dimensional (3D) models which have been produced using modern digital 3D documentation techniques, such as image-based modelling and terrestrial laser scanning. The reader is introduced to the history and importance \textendashas well as the peculiarities\textendash of the Macedonian tombs. In addition, the two tombs are described in detail mainly from an archaeological point of view The process of field data acquisition and processing to produce the 3D models are described. Simple and more or less standard methods were employed in acquiring the raw data. Processing was carried out using commercial software. The resulting 3D models and other documentation products are assessed for their accuracy and completeness. The decisions for the virtual anastylosis are explained in detail and the actual process is also described. The restored monuments are presented and evaluated by the conservation experts. Thus, it is shown how important virtual anastylosis of monuments is to archaeological researchers, as it enables them to conduct in-depth studies, without actually tampering with the monuments themselves. Digital 3D models are contributing to many disciplines, especially in archaeology, as they enable a wider audience to easily access both archaeological and geometric information as well as offering a high degree of interaction possibilities.},

keywords = {3D documentation, Image-Based modelling, Terrestrial laser scanning, virtual anastylosis},

pubstate = {published},

tppubtype = {article}

}

@article{Gkeli2020,

title = {A technical solution for 3D crowdsourced cadastral surveys},

author = {Maria Gkeli and Chryssy Potsiou and Charalabos Ioannidis},

url = {https://ideas.repec.org/a/eee/lauspo/v98y2020ics0264837719306660.html},

doi = {10.1016/j.landusepol.2019},

year  = {2020},

date = {2020-01-01},

urldate = {2020-01-01},

journal = {Land Use Policy},

volume = {98},

abstract = {The development of 3D property registration systems is indispensable for the spatial determination of property Rights, Restrictions and Responsibilities (RRR), the sustainable operation of property markets and the safeguarding of ownership in the highly urbanized world. Several developments in computer graphics, 3D modelling and rendering techniques have attracted the growing global interest in 3D cadastre. Since 2012, the Land Administration Domain Model (LADM ISO 19152) is adopted as the international standard for 2D and 3D cadastral data modelling. Developed legal procedures and prototype systems for 3D property rights registration provide interesting solutions for data acquisition and visualization but such approaches are time and cost demanding. In parallel, 2D cadastral surveying procedures have progressed significantly in reducing required time and cost, utilizing crowdsourcing methodology and mobile services.},

keywords = {3D cadastre, 3D modelling, 3D spatial data, Crowdsourcing, LADM, visualization},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2020,

title = {Correcting Image Refraction: Towards Accurate Aerial Image-Based Bathymetry Mapping in Shallow Waters},

author = {Panagiotis Agrafiotis and Konstantinos Karantzalos and Andreas Georgopoulos and Dimitrios Skarlatos},

url = {https://doi.org/10.3390/rs12020322 https://www.mdpi.com/2072-4292/12/2/322},

doi = {10.3390/rs12020322},

issn = {2072-4292},

year  = {2020},

date = {2020-01-01},

journal = {Remote Sens.},

volume = {12},

number = {2},

pages = {322},

publisher = {MDPI AG},

abstract = {Although aerial image-based bathymetric mapping can provide, unlike acoustic or LiDAR (Light Detection and Ranging) sensors, both water depth and visual information, water refraction poses significant challenges for accurate depth estimation. In order to tackle this challenge, we propose an image correction methodology, which first exploits recent machine learning procedures that recover depth from image-based dense point clouds and then corrects refraction on the original imaging dataset. This way, the structure from motion (SfM) and multi-view stereo (MVS) processing pipelines are executed on a refraction-free set of aerial datasets, resulting in highly accurate bathymetric maps. Performed experiments and validation were based on datasets acquired during optimal sea state conditions and derived from four different test-sites characterized by excellent sea bottom visibility and textured seabed. Results demonstrated the high potential of our approach, both in terms of bathymetric accuracy, as well as texture and orthoimage quality.},

keywords = {Aerial imagery, Bathymetry, Coastal mapping, DSM, Image correction, Machine Learning, Refraction correction, Seabed Mapping, SfM, UAV},

pubstate = {published},

tppubtype = {article}

}

@article{Katsichti2019,

title = {3D DOCUMENTATION OF FRAIL ARCHAEOLOGICAL FINDS USING LOW-COST INSTRUMENTATION},

author = {V Katsichti and Georgia Kontogianni and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W17/157/2019/},

doi = {10.5194/isprs-archives-XLII-2-W17-157-2019},

issn = {2194-9034},

year  = {2019},

date = {2019-11-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W17},

number = {2/W17},

pages = {157--164},

abstract = {Abstract. In archaeological excavations, many small fragments or artefacts are revealed whose fine details sometimes should be captured in 3D. In general, 3D documentation methods fall into two main categories: Range-Based modelling and Image-Based modelling. In Range Based modelling, a laser scanner (Time of Flight, Structured light, etc.) is used for the raw data acquisition in order to create the 3D model of an object. The above method is accurate enough but is still very expensive in terms of equipment. On the other hand, Image-Based modelling, is affordable because the equipment required is merely a camera with the appropriate lens, and possibly a turntable and a tripod. In this case, the 3D model of an object is created by suitable processing of images which are taken around the object with a large overlap. In this paper, emphasis is given on the effectiveness of 3D models of frail archaeological finds originate from the palatial site of Ayios Vasileios in Laconia in the south-eastern Peloponnese, using low-cost equipment and methods. The 3D model is also produced using various, mainly freeware, hence low-cost, software and the results are compared to those from a well-established commercial one.},

keywords = {Conservation, Foldio 360, Fresco fragments, Image-Based modelling},

pubstate = {published},

tppubtype = {article}

}

@article{Boutsi2019,

title = {An Integrated Approach to 3D Web Visualization of Cultural Heritage Heterogeneous Datasets},

author = {Argyro-Maria Boutsi and Charalabos Ioannidis and Sofia Soile},

url = {https://www.mdpi.com/2072-4292/11/21/2508},

doi = {10.3390/rs11212508},

issn = {2072-4292},

year  = {2019},

date = {2019-10-01},

urldate = {2019-10-01},

journal = {Remote Sens.},

volume = {11},

number = {21},

pages = {2508},

publisher = {MDPI AG},

abstract = {The evolution of the high-quality 3D archaeological representations from niche products to integrated online media has not yet been completed. Digital archives of the field often lack multimodal data interoperability, user interaction and intelligibility. A web-based cultural heritage archive that compensates for these issues is presented in this paper. The multi-resolution 3D models constitute the core of the visualization on top of which supportive documentation data and multimedia content are spatial and logical connected. Our holistic approach focuses on the dynamic manipulation of the 3D scene through the development of advanced navigation mechanisms and information retrieval tools. Users parse the multi-modal content in a geo-referenced way through interactive annotation systems over cultural points of interest and automatic narrative tours. Multiple 3D and 2D viewpoints are enabled in real-time to support data inspection. The implementation exploits front-end programming languages, 3D graphic libraries and visualization frameworks to handle efficiently the asynchronous operations and preserve the initial assets' accuracy. The choice of Greece's Meteora, UNESCO world site, as a case study accounts for the platform's applicability to complex geometries and large-scale historical environments.},

keywords = {3D visualization, Cultural heritage, Data retrieval, Interactivity, Photogrammetry, Remote sensing archaeology, structure from motion},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2019a,

title = {DepthLearn: Learning to correct the refraction on point clouds derived from aerial imagery for accurate dense shallow water bathymetry based on SVMs-fusion with LiDAR point clouds},

author = {Panagiotis Agrafiotis and Dimitrios Skarlatos and Andreas Georgopoulos and Konstantinos Karantzalos},

url = {https://www.mdpi.com/2072-4292/11/19/2225},

doi = {10.3390/rs11192225},

issn = {20724292},

year  = {2019},

date = {2019-09-01},

journal = {Remote Sens.},

volume = {11},

number = {19},

pages = {2225},

publisher = {MDPI AG},

abstract = {The determination of accurate bathymetric information is a key element for near offshore activities; hydrological studies, such as coastal engineering applications, sedimentary processes, hydrographic surveying, archaeological mapping and biological research. Through structure from motion (SfM) and multi-view-stereo (MVS) techniques, aerial imagery can provide a low-cost alternative compared to bathymetric LiDAR (Light Detection and Ranging) surveys, as it offers additional important visual information and higher spatial resolution. Nevertheless, water refraction poses significant challenges on depth determination. Till now, this problem has been addressed through customized image-based refraction correction algorithms or by modifying the collinearity equation. In this article, in order to overcome the water refraction errors in a massive and accurate way, we employ machine learning tools, which are able to learn the systematic underestimation of the estimated depths. In particular, an SVR (support vector regression) model was developed, based on known depth observations from bathymetric LiDAR surveys, which is able to accurately recover bathymetry from point clouds derived from SfM-MVS procedures. Experimental results and validation were based on datasets derived from different test-sites, and demonstrated the high potential of our approach. Moreover, we exploited the fusion of LiDAR and image-based point clouds towards addressing challenges of both modalities in problematic areas.},

keywords = {Aerial imagery, Bathymetry, Data integration, Fusion, LiDAR, Machine Learning, Point Cloud, Refraction effect, Seabed Mapping, SVM, UAV},

pubstate = {published},

tppubtype = {article}

}

@article{Kontogianni2019,

title = {EVALUATING THE EFFECT OF USING MIRRORS IN 3D RECONSTRUCTION OF SMALL ARTEFACTS},

author = {Georgia Kontogianni and M Lindstaedt and T P Kersten and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W15/633/2019/},

doi = {10.5194/isprs-archives-XLII-2-W15-633-2019},

issn = {2194-9034},

year  = {2019},

date = {2019-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W15},

number = {2/W15},

pages = {633--638},

publisher = {International Society for Photogrammetry and Remote Sensing},

abstract = {Abstract. Small artefacts pose many challenges to 3D documentation techniques due to their often complex details, which are very difficult to capture completely in 3D. Small objects may also have characteristics that are not optimal for 3D documentation, e.g. glossiness, shininess, textureless surfaces, etc. Furthermore, hidden parts of the artefact cause occlusions and obstructions, which may complicate the data acquisition process, since additional images or scan data are necessary in order to compensate for these restrictions. All these aspects increase acquisition and data processing times. Currently, the two main categories of 3D documentation methods are Image Based Modelling (IBM) and Range Based Modelling (RBM). In this paper, preliminary investigations aimed at evaluating the accuracy and performance of a front surface mirror in Image Based Modelling for small artefacts are presented. These results are then compared to a reference model generated from the artefact using a structured light system.},

keywords = {3D reconstruction, front surface mirror, small artefact},

pubstate = {published},

tppubtype = {article}

}

@article{Rallis2019,

title = {Choreographic Pattern Analysis from Heterogeneous Motion Capture Systems Using Dynamic Time Warping},

author = {Ioannis Rallis and Eftychios Protopapadakis and Athanasios Voulodimos and Nikolaos Doulamis and Anastasios Doulamis and Georgios Bardis},

url = {https://www.mdpi.com/2227-7080/7/3/56},

doi = {10.3390/technologies7030056},

issn = {2227-7080},

year  = {2019},

date = {2019-08-01},

journal = {Technologies},

volume = {7},

number = {3},

pages = {56},

publisher = {MDPI AG},

abstract = {The convention for the safeguarding of Intangible Cultural Heritage (ICH) by UNESCO highlights the equal importance of intangible elements of cultural heritage to tangible ones. One of the most important domains of ICH is folkloric dances. A dance choreography is a time-varying 3D process (4D modelling), which includes dynamic co-interactions among different actors, emotional and style attributes, and supplementary elements, such as music tempo and costumes. Presently, research focuses on the use of depth acquisition sensors, to handle kinesiology issues. The extraction of skeleton data, in real time, contains a significant amount of information (data and metadata), allowing for various choreography-based analytics. In this paper, a trajectory interpretation method for Greek folkloric dances is presented. We focus on matching trajectories' patterns, existing in a choreographic database, to new ones originating from different sensor types such as VICON and Kinect II. Then, a Dynamic Time Warping (DTW) algorithm is proposed to find out similarities/dissimilarities among the choreographic trajectories. The goal is to evaluate the performance of the low-cost Kinect II sensor for dance choreography compared to the accurate but of high-cost VICON-based choreographies. Experimental results on real-life dances are carried out to show the effectiveness of the proposed DTW methodology and the ability of Kinect II to localize dances in 3D space.},

keywords = {choreographic trajectory analysis, dance movement, dynamic time warping, Kinect, motion pattern matching, VICON},

pubstate = {published},

tppubtype = {article}

}

@article{Stampouloglou2019,

title = {3D DOCUMENTATION AND VIRTUAL ARCHAEOLOGICAL RESTORATION OF MACEDONIAN TOMBS},

author = {Maria Stampouloglou and Olympia Toska and Sevasti Tapinaki and Georgia Kontogianni and Margarita Skamantzari and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W11/1073/2019/},

doi = {10.5194/isprs-archives-XLII-2-W11-1073-2019},

issn = {2194-9034},

year  = {2019},

date = {2019-05-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W11},

pages = {1073--1080},

abstract = {Abstract. Archaeology as a science is based on finding and displaying the remains of the past. In recent years, with the progress of technology, the science of archeology has been expanding and evolving. Three-dimensional digitization has become an integral part of the archiving, documentation and restoration effort of cultural heritage, offering important benefits in studies for reconstruction and restoration tasks of architectural creations, archaeological sites, historic monuments and objects of art in general. The three-dimensional models are now available for many applications. In this paper such 3D models of two prominent Macedonian tombs in Northern Greece were exploited for their virtual restoration. Virtual restoration of monuments is of special importance to archaeological research, as it provides the necessary tools to investigate alternative solutions to the serious issue of archaeological restoration. These solutions do not interfere with the real monument, thus respecting its value and the international conventions. Digital 3D models have begun to be more beneficial in a science such as archaeology as they offer easy access to both archaeological and geometric information to a wider audience as well as a high degree of interaction possibilities with the user.},

keywords = {3D documentation, Image based modelling, laser scanning, virtual restoration},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2019,

title = {SHALLOW WATER BATHYMETRY MAPPING from UAV IMAGERY BASED on MACHINE LEARNING},

author = {P Agrafiotis and D Skarlatos and A Georgopoulos and K Karantzalos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W10/9/2019/},

doi = {10.5194/isprs-archives-XLII-2-W10-9-2019},

issn = {21949050},

year  = {2019},

date = {2019-04-01},

journal = {ISPRS Ann. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {42},

number = {2/W10},

pages = {9--16},

abstract = {The determination of accurate bathymetric information is a key element for near offshore activities, hydrological studies such as coastal engineering applications, sedimentary processes, hydrographic surveying as well as archaeological mapping and biological research. UAV imagery processed with Structure from Motion (SfM) and Multi View Stereo (MVS) techniques can provide a low-cost alternative to established shallow seabed mapping techniques offering as well the important visual information. Nevertheless, water refraction poses significant challenges on depth determination. Till now, this problem has been addressed through customized image-based refraction correction algorithms or by modifying the collinearity equation. In this paper, in order to overcome the water refraction errors, we employ machine learning tools that are able to learn the systematic underestimation of the estimated depths. In the proposed approach, based on known depth observations from bathymetric LiDAR surveys, an SVR model was developed able to estimate more accurately the real depths of point clouds derived from SfM-MVS procedures. Experimental results over two test sites along with the performed quantitative validation indicated the high potential of the developed approach.},

keywords = {Bathymetry, Machine Learning, Point Cloud, Refraction effect, Seabed Mapping, SVM, UAV},

pubstate = {published},

tppubtype = {article}

}

@article{Delegou2019,

title = {A Multidisciplinary Approach for Historic Buildings Diagnosis: The Case Study of the Kaisariani Monastery},

author = {Ekaterini T Delegou and Georgia Mourgi and Elisavet Tsilimantou and Charalabos Ioannidis and Antonia Moropoulou},

url = {https://www.mdpi.com/2571-9408/2/2/79},

doi = {10.3390/heritage2020079},

issn = {2571-9408},

year  = {2019},

date = {2019-04-01},

journal = {Heritage},

volume = {2},

number = {2},

pages = {1211--1232},

abstract = {In this work, a multi-disciplinary approach regarding diagnostic study processes is presented, using as an example the Catholicon of Kaisariani Monastery in Attica, Greece. Kaisariani Monastery is considered one of the most important Byzantine architectural complexes in Greece. The Catholicon of Kaisariani Monastery was built during the middle Byzantine period, and has undergone many reconstructions during the centuries. It is a semi-complex, four-columned, cross-in-square church, with a cloisonn\'{e} masonry. The suggested diagnostic processes included the creation of multidisciplinary thematic maps in Computer Aided Design (CAD) environment, which incorporated: (a) data of historical and architectural documentation; (b) data of geometric documentation; and (c) data of building materials characterization and decay diagnosis. The historical and general architectural data were acquired by thorough bibliographical/archival research. Geometric documentation data were acquired by three-dimensional (3D) laser scanner for the creation of the Catholicon section drawings, whereas image based photogrammetric techniques were utilized for the creation of a 3D textured model, from which orthoimages and architectural drawings of the Catholicon fa\c{c}ades were developed. In parallel, characterization of building materials and identification of decay patterns took place after the onsite application of the nondestructive techniques of digital microscopy, infrared thermography and ground penetrating radar. These vast array kinds of data were elaborated and integrated into the architectural drawings, developing thematic maps that record and represent the current preservation state of the monument, a concerning major construction phases, the most important conservation intervention projects, building materials and decay. Furthermore, data quantification regarding the extent of building materials and decay at each monument's fa\c{c}ade took place. Therefore, correlation and better understanding of the environmental impact on building materials according to fa\c{c}ade orientation and historical data, e.g., construction phases, was accomplished. In conclusion, the presented processes are multidisciplinary tasks that require collaboration among architects, surveyor engineers and materials scientists/engineers. They are also prerequisites for the planning and application of compatible and efficient conservation/restoration interventions, for the ultimate goal of the sustainable protection of a monument.},

keywords = {church, Cultural heritage, diagnostic study, geometric documentation, multi-disciplinary approach, non-destructive techniques, sustainable protection, thematic maps},

pubstate = {published},

tppubtype = {article}

}

@article{Maltezos2019,

title = {Building Extraction From LiDAR Data Applying Deep Convolutional Neural Networks},

author = {Evangelos Maltezos and Anastasios Doulamis and Nikolaos Doulamis and Charalabos Ioannidis},

url = {https://ieeexplore.ieee.org/document/8465968/},

doi = {10.1109/LGRS.2018.2867736},

issn = {1545-598X},

year  = {2019},

date = {2019-01-01},

journal = {IEEE Geosci. Remote Sens. Lett.},

volume = {16},

number = {1},

pages = {155--159},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Tapinaki2019,

title = {3D IMAGE BASED GEOMETRIC DOCUMENTATION OF A MEDIEVAL FORTRESS},

author = {S Tapinaki and M Skamantzari and R Chliverou and V Evgenikou and A M Konidi and E Ioannatou and A Mylonas and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W9/699/2019/},

doi = {10.5194/isprs-archives-XLII-2-W9-699-2019},

issn = {2194-9034},

year  = {2019},

date = {2019-01-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W9},

pages = {699--705},

abstract = {Abstract. The detailed and thorough documentation of monuments is a rather complex process that requires the application of the best available state of the art techniques in order to preserve, restore, promote and make cultural heritage accessible to the public. This paper presents the 3D Geometric Documentation of a part of the medieval fortress of Chios, focussing in particular on the practical challenges which the object presented. The case study is a part of the fortified construction, consisting of a bastion, a watch tower on top of this bastion and a significant part of its walls with a surface of about 1053m2 in total. The goal of the survey was to produce an accurate 3D detailed textured model and a series of coloured orthophotos and 2D vector drawings. The documentation methods employed included close-range automated photogrammetry and image-based modelling, terrestrial laser scanning and topographic surveys, an ideal combination of methods.},

keywords = {3D model, laser scanning, Orthophoto, Photogrammetry, UAV},

pubstate = {published},

tppubtype = {article}

}

@article{tserpes2019strand,

title = {Strand: scalable trilateration with Node. js},

author = {Konstantinos Tserpes and Maria Pateraki and Iraklis Varlamis},

year  = {2019},

date = {2019-01-01},

journal = {J. Cloud Comput.},

volume = {8},

number = {1},

pages = {1--16},

publisher = {SpringerOpen},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Gkeli2019,

title = {Crowdsourced 3D cadastral surveys: looking towards the next 10 years},

author = {Maria Gkeli and Chryssy Potsiou and Charalabos Ioannidis},

url = {https://ideas.repec.org/a/kap/jgeosy/v21y2019i1d10.1007_s10109-018-0287-0.html},

doi = {10.1007/s10109-018-0287-0},

year  = {2019},

date = {2019-01-01},

journal = {Journal of Geographical Systems},

volume = {21},

number = {1},

pages = {61-87},

publisher = {Springer Verlag},

abstract = {Rapidly growing cities, multiple uses of urban space and the complexity of overlapping property rights require various types of rights to be registered and handled in a uniform and reliable way, considering the third dimension. The adoption of automated and low-cost but reliable procedures for cadastral surveys and for the capture and processing of cadastral data, as well as the use of modern Information Technology (IT) tools and m-services, is the beginning of a new cadastral evolution. 3D-crowdsourced cadastral data capture has huge potential and may soon facilitate the work of National Mapping Agencies (NMAs). In this paper, an innovative fit-for-purpose procedure is designed and initially tested that aims to save time and costs and to provide a modern technical solution for the initial collection, registration and visualization of 3D cadastral data. An open-source, mobile application for the acquisition of 3D crowdsourced cadastral data and 3D modelling and visualization of property units is developed, tested and presented. The proposed technical procedure is adjustable and may be used in both the developed and the developing world. The geometric accuracy of the final product depends on the geometric accuracy of the basemaps used. The developed application is tested on a multi-story building in an urban area of Larisa, in Greece. An initial evaluation of the procedure and the final product, in terms of its usability, affordability, reliability and implementation duration, is conducted. The first results are satisfactory and may lead to a fit-for-purpose procedure for a 3D cadastre for all in the future.},

keywords = {3D cadastre, 3D modelling, Crowdsourcing, Land administration},

pubstate = {published},

tppubtype = {article}

}

@article{Verykokou2018,

title = {A PHOTOGRAMMETRY-BASED STRUCTURE FROM MOTION ALGORITHM USING ROBUST ITERATIVE BUNDLE ADJUSTMENT TECHNIQUES},

author = {Styliani Verykokou and Charalabos Ioannidis},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/IV-4-W6/73/2018/},

doi = {10.5194/isprs-annals-IV-4-W6-73-2018},

issn = {2194-9050},

year  = {2018},

date = {2018-09-01},

journal = {ISPRS Ann. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {IV-4/W6},

pages = {73--80},

abstract = {Abstract. The purpose of this paper is the presentation of a novel algorithm for automatic estimation of the exterior orientation parameters of image datasets, which can be applied in the case that the scene depicted in the images has a planar surface (e.g., roof of a building). The algorithm requires the measurement of four coplanar ground control points (GCPs) in only one image. It uses a template matching method combined with a homography-based technique for transfer of the GCPs in another image, along with an incremental photogrammetry-based Structure from Motion (SfM) workflow, coupled with robust iterative bundle adjustment methods that reject any remaining outliers, which have passed through the checks and geometric constraints imposed during the image matching procedure. Its main steps consist of (i) determination of overlapping images without the need for GPS/INS data; (ii) image matching and feature tracking; (iii) estimation of the exterior orientation parameters of a starting image pair; and (iv) photogrammetry-based SfM combined with iterative bundle adjustment methods. A developed software solution implementing the proposed algorithm was tested using a set of UAV oblique images. Several tests were performed for the assessment of the errors and comparisons with well-established commercial software were made, in terms of automation and correctness of the computed exterior orientation parameters. The results show that the estimated orientation parameters via the proposed solution have comparable accuracy with those ones computed through the commercial software using the highest possible accuracy settings; in addition, double manual work was required by the commercial software compared to the proposed solution.},

keywords = {Bundle Adjustment, Coplanar Feature Points, exterior orientation, Homography, Oblique Images, structure from motion, Template Matching},

pubstate = {published},

tppubtype = {article}

}

@article{Maltezos2018,

title = {Plane detection of polyhedral cultural heritage monuments: The case of tower of winds in Athens},

author = {Evangelos Maltezos and Charalabos Ioannidis},

url = {https://linkinghub.elsevier.com/retrieve/pii/S2352409X17305126},

doi = {10.1016/j.jasrep.2018.03.036},

issn = {2352409X},

year  = {2018},

date = {2018-06-01},

journal = {J. Archaeol. Sci. Reports},

volume = {19},

pages = {562--574},

publisher = {Elsevier Ltd},

abstract = {This study introduces an efficient and easy to implement plane detection approach towards the extraction of high-level information from 3D point clouds associated with polyhedral cultural heritage monuments. An adapted version of the randomized Hough transform (RHT) called “adaptive point randomized Hough transform” (APRHT) and a multiscale framework in terms of Level of Detail 1 (LoD 1) and LoD 2 are proposed. A dense image matching point cloud of an octagonal tower called Tower of Winds, which is situated on the northern foot of the Acropolis hill in Athens was used. A pre-process is carried out to extract points associated with the vertical structural elements. Then a plane detection process is performed in terms of LoD 1 to calculate the plane parameters ($theta$, $phi$ and $rho$) of each of the eight planar surfaces using a coarse form of the entire monument, that is, a sparse point cloud extracted via subsampling process. A mask of one representative detected planar surface is used to clip the initial point cloud with the initial point density. Then, a second plane detection process in terms of LoD 2 at the clipped point cloud is implemented to calculate the corresponding accurate plane parameters. The results are useful for cultural heritage preservation purposes and illustrate the robustness, efficiency and the rapidity of the proposed framework.},

keywords = {Dense image matching, Plane detection, Point Cloud, Randomized Hough transform},

pubstate = {published},

tppubtype = {article}

}

@article{Verykokou2018a,

title = {Oblique aerial images: a review focusing on georeferencing procedures},

author = {Styliani Verykokou and Charalabos Ioannidis},

url = {https://www.tandfonline.com/action/journalInformation?journalCode=tres20},

doi = {10.1080/01431161.2018.1444294},

issn = {0143-1161},

year  = {2018},

date = {2018-06-01},

journal = {Int. J. Remote Sens.},

volume = {39},

number = {11},

pages = {3452--3496},

abstract = {The automatic processing of oblique aerial images is currently one of the most attractive topics in the fields of photogrammetry, remote sensing and computer vision. This kind of images has gained popularity throughout the last years, as it enables depiction of both vertical and horizontal structures of the urban environment, being ideal for various photogrammetric applications, apart from visualiza-tion and interpretation purposes. In most cases, the georeferencing of the images is indispensable for their metric exploitation, usually in terms of computation of their camera exterior orientation parameters. For other applications, georeferencing by means of image orthorectification is required, whereas a simple georeferencing in terms of mapping of the center point of the images or the outline of their footprint or image rectification via a 2D transformation also suffices in some cases. However, oblique airborne images pose several challenges in automated georeferencing procedures, due to complex image geometry and strongly varying appearance between images of the same scene taken from different viewing angles. In this paper, a thorough literature review is conducted in order to inform about the recent research in georeferencing of datasets including oblique aerial imagery. The review starts with a classification of oblique aerial imagery and a presentation of the most commonly used camera configurations for oblique imagery acquisition. A brief presentation of their history along with old applications is then made, followed by a categorization of the literature regarding state-of-the-art georeferencing procedures as well as other research trends and applications using oblique aerial images. Then, a more in-depth description of recent research on georeferencing of oblique image datasets is presented. Finally, the significant points, research results and conclusions derived from the literature are discussed, so that they can be utilized by future researchers in the development of georeferencing methods targeted to oblique airborne imagery. ARTICLE HISTORY},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kontogianni2018,

title = {EXPLOITING MIRRORS IN 3D RECONSTRUCTION OF SMALL ARTEFACTS},

author = {Georgia Kontogianni and A T Thomaidis and Regina Chliverou and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2/531/2018/},

doi = {10.5194/isprs-archives-XLII-2-531-2018},

issn = {2194-9034},

year  = {2018},

date = {2018-05-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2},

number = {2},

pages = {531--537},

publisher = {International Society for Photogrammetry and Remote Sensing},

abstract = {3D reconstruction of small artefacts is very significant in order to capture the details of the whole object irrespective of the documentation method which is used (Ranged Based or Image Based). Sometimes it is very difficult to achieve it because of hidden parts, occlusions, and obstructions which the object has. Hence, more data are necessary in order to 3D digitise the whole of the artefact leading to increased time for collecting and consequently processing the data. A methodology is necessary in order to reduce the collection of the data and therefore their processing time especially in cases of mass digitisation. So in this paper, the use of mirrors in particular high-quality mirrors in the data acquisition phase for the 3D reconstruction of small artefacts is investigated. Two case studies of 3D reconstruction are presented: the first one concerns Range-Based modelling especially a Time of Flight laser scanner is utilised and in the second one Image-Based modelling technique is implemented.},

keywords = {Image-Based modelling, Mirrors, Range-based modelling, Small artefacts},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2018,

title = {Underwater photogrammetry in very shallow waters: Main challenges and caustics effect removal},

author = {P Agrafiotis and D Skarlatos and T Forbes and C Poullis and M Skamantzari and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2/15/2018/},

doi = {10.5194/isprs-archives-XLII-2-15-2018},

issn = {16821750},

year  = {2018},

date = {2018-05-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {2},

pages = {15--22},

publisher = {International Society for Photogrammetry and Remote Sensing},

abstract = {In this paper, main challenges of underwater photogrammetry in shallow waters are described and analysed. The very short camera to object distance in such cases, as well as buoyancy issues, wave effects and turbidity of the waters are challenges to be resolved. Additionally, the major challenge of all, caustics, is addressed by a new approach for caustics removal (Forbes et al., 2018) which is applied in order to investigate its performance in terms of SfM-MVS and 3D reconstruction results. In the proposed approach the complex problem of removing caustics effects is addressed by classifying and then removing them from the images. We propose and test a novel solution based on two small and easily trainable Convolutional Neural Networks (CNNs). Real ground truth for caustics is not easily available. We show how a small set of synthetic data can be used to train the network and later transfer the le arning to real data with robustness to intra-class variation. The proposed solution results in caustic-free images which can be further used for other tasks as may be needed.},

keywords = {Caustics, CNN, SfM MVS, Underwater 3D reconstruction},

pubstate = {published},

tppubtype = {article}

}

@article{Apostolopoulos2018,

title = {A new model for cadastral surveying using crowdsourcing},

author = {K Apostolopoulos and M Geli and P Petrelli and C Potsiou and C Ioannidis},

url = {https://www.tandfonline.com/doi/abs/10.1080/00396265.2016.1253522},

doi = {10.1080/00396265.2016.1253522},

issn = {17522706},

year  = {2018},

date = {2018-03-01},

journal = {Surv. Rev.},

volume = {50},

number = {359},

pages = {122--133},

publisher = {Taylor and Francis Ltd.},

abstract = {A ‘fit-for-purpose' approach is developed, tested and presented for cadastral surveys through increased owners' participation using new technology and m-government services. Three case studies are reported, for urban, suburban and rural areas, with a combined use of two mobile applications: a commercial software package (ESRI's Collector for ArcGIS) and an opensource self-developed application named BoundGeometry. The parameters of time, quality and accuracy are assessed and the identified difficulties are classified. It is concluded that the method is applicable both in developed and developing countries, and each time adjustable to the available infrastructure.},

keywords = {Cadastre, Crowdsourcing, Gamification, Mobile device, VGI},

pubstate = {published},

tppubtype = {article}

}

@article{Voulodimos2018,

title = {Deep Learning for Computer Vision: A Brief Review},

author = {Athanasios Voulodimos and Nikolaos Doulamis and Anastasios Doulamis and Eftychios Protopapadakis},

url = {https://www.hindawi.com/journals/cin/2018/7068349/},

doi = {10.1155/2018/7068349},

issn = {1687-5265},

year  = {2018},

date = {2018-01-01},

journal = {Comput. Intell. Neurosci.},

volume = {2018},

pages = {1--13},

abstract = {Over the last years deep learning methods have been shown to outperform previous state-of-the-art machine learning techniques in several fields, with computer vision being one of the most prominent cases. This review paper provides a brief overview of some of the most significant deep learning schemes used in computer vision problems, that is, Convolutional Neural Networks, Deep Boltzmann Machines and Deep Belief Networks, and Stacked Denoising Autoencoders. A brief account of their history, structure, advantages, and limitations is given, followed by a description of their applications in various computer vision tasks, such as object detection, face recognition, action and activity recognition, and human pose estimation. Finally, a brief overview is given of future directions in designing deep learning schemes for computer vision problems and the challenges involved therein.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kossieris2017,

title = {Developing a low-cost system for 3d data acquisition},

author = {S Kossieris and O Kourounioti and P Agrafiotis and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W8/119/2017/},

doi = {10.5194/isprs-archives-XLII-2-W8-119-2017},

issn = {16821750},

year  = {2017},

date = {2017-11-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {2W8},

pages = {119--126},

abstract = {In this paper, a developed low-cost system is described, which aims to facilitate 3D documentation fast and reliably by acquiring the necessary data in outdoor environment for the 3D documentation of facades especially in the case of very narrow streets. In particular, it provides a viable solution for buildings up to 8-10m high and streets as narrow as 2m or even less. In cases like that, it is practically impossible or highly time-consuming to acquire images in a conventional way. This practice would lead to a huge number of images and long processing times. The developed system was tested in the narrow streets of a medieval village on the Greek island of Chios. There, in order to by-pass the problem of short taking distances, it was thought to use high definition action cameras together with a 360¢camera, which are usually provided with very wide-angle lenses and are capable of acquiring images, of high definition, are rather cheap and, most importantly, extremely light. Results suggest that the system can perform fast 3D data acquisition adequate for deliverables of high quality.},

keywords = {360° camera, Action camera, Facades, Low-cost 3D, Narrow streets, Orthoimage},

pubstate = {published},

tppubtype = {article}

}

@article{Kazanis2017,

title = {DEVELOPING A VIRTUAL MUSEUM FOR THE ANCIENT WINE TRADE IN EASTERN MEDITERRANEAN},

author = {Sawas Kazanis and Georgia Kontogianni and Regina Chliverou and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W5/399/2017/},

doi = {10.5194/isprs-archives-XLII-2-W5-399-2017},

issn = {2194-9034},

year  = {2017},

date = {2017-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W5},

pages = {399--405},

abstract = {Digital technologies for representing cultural heritage assets of any size are already maturing. Technological progress has greatly enhanced the art of virtual representation and, as a consequence, it is all the more appealing to the general public and especially to younger generations. The game industry has played a significant role towards this end and has led to the development of edutainment applications. The digital workflow implemented for developing such an application is presented in this paper. A virtual museum has been designed and developed, with the intention to convey the history of trade in the Eastern Mediterranean area, focusing on the Aegean Sea and five productive cities-ports, during a period of more than 500 years. Image based modeling methodology was preferred to ensure accuracy and reliability. The setup in the museum environment, the difficulties encountered and the solutions adopted are discussed, while processing of the images and the production and finishing of the 3D models are described in detail. The virtual museum and edutainment application, MEDWINET, has been designed and developed with the intention to convey the essential information of the wine production and trade routes in the Eastern Mediterranean basin. The user is able to examine the 3D models of the amphorae, while learning about their production and use for trade during the centuries. The application has been evaluated and the results are also discussed.},

keywords = {3D models, amphora, stamped handles, Stoa of Attalos, Virtual Museum},

pubstate = {published},

tppubtype = {article}

}

@article{Kontogianni2017a,

title = {ENHANCING CLOSE-UP IMAGE BASED 3D DIGITISATION WITH FOCUS STACKING},

author = {Georgia Kontogianni and Regina Chliverou and A Koutsoudis and G Pavlidis and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W5/421/2017/},

doi = {10.5194/isprs-archives-XLII-2-W5-421-2017},

issn = {2194-9034},

year  = {2017},

date = {2017-08-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W5},

pages = {421--425},

abstract = {The 3D digitisation of small artefacts is a very complicated procedure because of their complex morphological feature structures, concavities, rich decorations, high frequency of colour changes in texture, increased accuracy requirements etc. Image-based methods present a low cost, fast and effective alternative because laser scanning does not meet the accuracy requirements in general. A shallow Depth of Field (DoF) affects the image-based 3D reconstruction and especially the point matching procedure. This is visible not only in the total number of corresponding points but also in the resolution of the produced 3D model. The extension of the DoF is a very important task that should be incorporated in the data collection to attain a better quality of the image set and a better 3D model. An extension of the DoF can be achieved with many methods and especially with the use of the focus stacking technique. In this paper, the focus stacking technique was tested in a real-world experiment to digitise a museum artefact in 3D. The experiment conditions include the use of a full frame camera equipped with a normal lens (50mm), with the camera being placed close to the object. The artefact has already been digitised with a structured light system and that model served as the reference model in which 3D models were compared and the results were presented.},

keywords = {3D reconstruction, Focus Stacking, small artifacts},

pubstate = {published},

tppubtype = {article}

}

@article{Adamopoulos2017,

title = {MULTI-SENSOR DOCUMENTATION OF METRIC AND QUALITATIVE INFORMATION OF HISTORIC STONE STRUCTURES},

author = {E Adamopoulos and Elisavet Tsilimantou and V Keramidas and Maria Apostolopoulou and M Karoglou and Sevasti Tapinaki and Charalabos Ioannidis and Andreas Georgopoulos and Antonia Moropoulou},

url = {https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/IV-2-W2/1/2017/},

doi = {10.5194/isprs-annals-IV-2-W2-1-2017},

issn = {2194-9050},

year  = {2017},

date = {2017-08-01},

journal = {ISPRS Ann. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {IV-2/W2},

pages = {1--8},

abstract = {This paper focuses on the integration of multi-sensor techniques regarding the acquisition, processing, visualisation and management of data regarding historic stone structures. The interdisciplinary methodology that is carried out here comprises of two parts. In the first part, the acquisition of qualitative and quantitative data concerning the geometry, the materials and the degradation of the tangible heritage asset each time, is discussed. The second part, refers to the analysis, management and visualization of the interrelated data by using spatial information technologies. Through the paradigm of the surveying of the ancient temple of Pythian Apollo at Acropolis of Rhodes, Rhodes Island, Greece, it is aimed to highlight the issues deriving from the separate application of documentation procedures and how the fusion of these methods can contribute effectively to ensure the completeness of the measurements for complex structures. The surveying results are further processed to be compatible and integrated with GIS. Also, the geometric documentation derivatives are combined with environmental data and the results of the application of non-destructive testing and evaluation techniques in situ and analytical techniques in lab after sampling. GIS operations are utilized to document the building materials but also to model and to analyse the decay extent and patterns. Detailed surface measurements and geo-processing analysis are executed. This integrated approach, helps the assessment of past interventions on the monument, identify main causes of damage and decay, and finally assist the decision making on the most compatible materials and techniques for protection and restoration works.},

keywords = {Built Heritage, Decay, Documentation, Geographic Information System, Materials},

pubstate = {published},

tppubtype = {article}

}

@article{Kontogianni2017c,

title = {Utilising 3D Realistic Models in Serious Games for Cultural Heritage},

author = {Georgia Kontogianni and Christos Koutsaftis and Margarita Skamantzari and Christina Chrysanthopoulou and Andreas Georgopoulos},

url = {http://services.igi-global.com/resolvedoi/resolve.aspx?doi=10.4018/IJCMHS.2017070102},

doi = {10.4018/IJCMHS.2017070102},

issn = {2473-5345},

year  = {2017},

date = {2017-07-01},

journal = {Int. J. Comput. Methods Herit. Sci.},

volume = {1},

number = {2},

pages = {21--46},

abstract = {In the cultural heritage field, many Serious Games applications have been developed whose goal is to educate players and users not particularly specialized or familiar with this field. On the other hand, 3D models of cultural heritage objects created with precise 3D modelling methods can be a very useful asset for these applications. In this paper a composite Serious Game for the Stoa of Attalos, a prominent monument in the Ancient Athens Agora, is developed and presented. 3D models are used, which were produced mainly with automated image based modelling techniques. The creation of the 3D models is described and presented along with the development of the application, which offers three options for the player. These options are: a quiz game, a 3D visual quiz and a virtual museum. The user interaction is described and, based on an evaluation questionnaire, the application is assessed by a group of people in the Cultural Heritage field.},

keywords = {3D models, Cultural heritage, Serious games},

pubstate = {published},

tppubtype = {article}

}

@article{Georgopoulos2017,

title = {Merging geometric documentation with materials characterization and analysis of the history of the holy aedicule in the church of the holy sepulchre in Jerusalem},

author = {A Georgopoulos and E Lambrou and G Pantazis and P Agrafiotis and A Papadaki and L Kotoula and K Lampropoulos and E Delegou and M Apostolopoulou and M Alexakis and A Moropoulou},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-5-W1/487/2017/},

doi = {10.5194/isprs-Archives-XLII-5-W1-487-2017},

issn = {16821750},

year  = {2017},

date = {2017-05-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {5W1},

pages = {487--494},

abstract = {The National Technical University of Athens undertook the compilation of an "Integrated Diagnostic Research Project and Strategic Planning for Materials, Interventions Conservation and Rehabilitation of the Holy Aedicule of the Church of the Holy Sepulchre in Jerusalem". This paper focuses on the work merging the geometric documentation with the characterization of materials, the identification of building phases and the diagnosis of decay and pathology through the use of analytical and non-destructive techniques. Through this integrated approach, i.e. through the documentation and characterization of the building materials, through the diagnosis of decay and pathology, through the accurate geometric documentation of the building and through the non-destructive prospection of its internal structure, it was feasible to identify the construction phases of the Holy Aedicule, identifying the remnants of the preserved earlier constructions and the original monolithic Tomb. This work, thus, demonstrates that the adoption of an interdisciplinary approach for integrated documentation is a powerful tool for a better understanding of monuments, both in terms of its structural integrity, as well as in terms of its state of preservation, both prerequisites for effective rehabilitation.},

keywords = {Geomatics, geometric documentation, Image based modelling, Materials, non-destructive techniques, Terrestrial laser scanning},

pubstate = {published},

tppubtype = {article}

}

@article{Kontogianni2017b,

title = {INVESTIGATING THE EFFECT OF FOCUS STACKING ON SFM-MVS ALGORITHMS},

author = {Georgia Kontogianni and Regina Chliverou and A Koutsoudis and G Pavlidis and Andreas Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W3/385/2017/},

doi = {10.5194/isprs-archives-XLII-2-W3-385-2017},

issn = {2194-9034},

year  = {2017},

date = {2017-02-01},

journal = {ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci.},

volume = {XLII-2/W3},

pages = {385--389},

abstract = {The Depth of Field (DoF) is a vital factor in photogrammetric applications. Its effect is in most cases pretty obvious especially when capturing small artefacts. It is very important to observe its behaviour as it affects the ability to capture all the details of an object. Focus stacking is a technique in computational photography, in which a set of images focused on different planes with limited DoF are combined in order to considerably extend the DoF. Today, there is a number of focus stacking methods that can be applied in order to produce a full-focus image. In this paper, we investigate the application and effects of focus stacking on SfM-MVS 3D reconstruction. Specifically, our experiment involves the 3D reconstruction of a selected artefact using both traditional all-focus photography and focus stacking. The artefact has already been digitised with a high accuracy and resolution structured light 3D scanner, and that 3D model served as the reference model, with which SfM models were compared. We discuss on these fist results and present some preliminary assessment on the application of focus stacking for the SfM-MVS-based 3D reconstruction.},

keywords = {3D reconstruction, Focus Stacking, SfM-MVS},

pubstate = {published},

tppubtype = {article}

}

@article{Kouimtzoglou2017,

title = {Image-based 3D reconstruction data as an analysis and documentation tool for architects: The case of Plaka bridge in Greece},

author = {T Kouimtzoglou and E K Stathopoulou and P Agrafiotis and A Georgopoulos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W3/391/2017/},

doi = {10.5194/isprs-archives-XLII-2-W3-391-2017},

issn = {16821750},

year  = {2017},

date = {2017-02-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {2W3},

pages = {391--397},

abstract = {Modern advances in the field of image-based 3D reconstruction of complex architectures are valuable tools that may offer the researchers great possibilities integrating the use of such procedures in their studies. In the same way that photogrammetry was a well-known useful tool among the cultural heritage community for years, the state of the art reconstruction techniques generate complete and easy to use 3D data, thus enabling engineers, architects and other cultural heritage experts to approach their case studies in an exhaustive and efficient way. The generated data can be a valuable and accurate basis upon which further plans and studies will be drafted. These and other aspects of the use of image-based 3D data for architectural studies are to be presented and analysed in this paper, based on the experience gained from a specific case study, the Plaka Bridge. This historic structure is of particular interest, as it was recently lost due to extreme weather conditions and serves as a strong proof that preventive actions are of utmost importance in order to preserve our common past.},

keywords = {Architecture, Cultural heritage, Image-based 3D reconstruction, Photogrammetry},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2017a,

title = {The effect of underwater imagery radiometry on 3D reconstruction and orthoimagery},

author = {P Agrafiotis and G I Drakonakis and A Georgopoulos and D Skarlatos},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W3/25/2017/},

doi = {10.5194/isprs-archives-XLII-2-W3-25-2017},

issn = {16821750},

year  = {2017},

date = {2017-02-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {2W3},

pages = {25--31},

abstract = {The work presented in this paper investigates the effect of the radiometry of the underwater imagery on automating the 3D reconstruction and the produced orthoimagery. Main aim is to investigate whether pre-processing of the underwater imagery improves the 3D reconstruction using automated SfM - MVS software or not. Since the processing of images either separately or in batch is a time-consuming procedure, it is critical to determine the necessity of implementing colour correction and enhancement before the SfM - MVS procedure or directly to the final orthoimage when the orthoimagery is the deliverable. Two different test sites were used to capture imagery ensuring different environmental conditions, depth and complexity. Three different image correction methods are applied: A very simple automated method using Adobe Photoshop, a developed colour correction algorithm using the CLAHE (Zuiderveld, 1994) method and an implementation of the algorithm described in Bianco et al., (2015). The produced point clouds using the initial and the corrected imagery are then being compared and evaluated.},

keywords = {SfM-MVS, Underwater 3D reconstruction, Underwater image enhancement},

pubstate = {published},

tppubtype = {article}

}

@article{Agrafiotis2017b,

title = {3D modelling the invisible using ground penetrating radar},

author = {P Agrafiotis and K Lampropoulos and A Georgopoulos and A Moropoulou},

url = {https://www.int-arch-photogramm-remote-sens-spatial-inf-sci.net/XLII-2-W3/33/2017/},

doi = {10.5194/isprs-archives-XLII-2-W3-33-2017},

issn = {16821750},

year  = {2017},

date = {2017-02-01},

journal = {Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch.},

volume = {42},

number = {2W3},

pages = {33--37},

abstract = {An interdisciplinary team from the National Technical University of Athens is performing the restoration of the Holy Aedicule, which covers the Tomb of Christ within the Church of the Holy Sepulchre in Jerusalem. The first important task was to geometrically document the monument for the production of the necessary base material on which the structural and material prospection studies would be based. One task of this action was to assess the structural behavior of this edifice in order to support subsequent works. It was imperative that the internal composition of the construction be documented as reliably as possible. To this end several data acquisition techniques were employed, among them ground penetrating radar. Interpretation of these measurements revealed the position of the rock, remnants of the initial cave of the bunal of Christ. This paper reports on the methodology employed to construct the 3D model of the rock and introduce it into the 3D model of the whole building, thus enhancing the information about the structure. The conversion of the radargrams to horizontal sections of the rock is explained and the construction of the 3D model and its insertion into the 3D model of the Holy Aedicule is descnbed.},

keywords = {3D modelling, Ground penetrating radar (GPR), Holy aedicule},

pubstate = {published},

tppubtype = {article}

}

@article{Hatzopoulos2017,

title = {Use of various surveying technologies to 3D digital mapping and modelling of cultural heritage structures for maintenance and restoration purposes: The Tholos in Delphi, Greece},

author = {John N Hatzopoulos and Dimitrios Stefanakis and Andreas Georgopoulos and Sevasti Tapinaki and Volonakis Pantelis and Ioannis Liritzis},

doi = {10.5281/zenodo.1048937},

issn = {22418121},

year  = {2017},

date = {2017-01-01},

journal = {Mediterr. Archaeol. Archaeom.},

volume = {17},

number = {3},

pages = {311--336},

publisher = {University of AEGEAN},

abstract = {This work was developed to train graduate students as part of the Delphi4Delphi project dealing with the digital reconstruction of the archaeological site of Delphi. In this part of the project, various technologies were used for 3-d digital mapping cultural heritage structures for maintenance and restoration purposes. The use of various surveying technologies such as UAS, Total station, digital camera, Lidar scanner and GPS to map in 3d the remaining of the monument Tholos and the surrounding area in Delphi Greece and based on such mapping to restore the entire structure is covered in detail. The remains of such monuments are a few columns standing up joined with original elements on top. In this part of the project GPS was used to establish the reference system, total station was used to measure a number of control points for UAS, close range photogrammetry and Lidar scanner, UAS was used to map precisely the surrounding area together with the structure, close range photogrammetry and Lidar scanner were used to map the vertical surfaces of the structure. Processing of above data from all surveying technologies created enough point cloud to map precisely the remains of the structure and expand their architectural design to precisely restore the entire Tholos monument. Also all digital data are used by software for the construction of 3D terrain and 3D models which when inserted into Game Engines software aim at the creation of educational scenarios.},

keywords = {Education, Game engine, Laser scanner, Monument mapping, Photogrammetry, Restoration, Surveying, UAS},

pubstate = {published},

tppubtype = {article}

}

@article{Suma2016,

title = {Evaluation of the effectiveness of HDR tone-mapping operators for photogrammetric applications},

author = {Rossella Suma and Georgia Stavropoulou and Elisavet K Stathopoulou and Luc {Van Gool} and Andreas Georgopoulos and Alan Chalmers},

url = {http://polipapers.upv.es/index.php/var/article/view/6319},

doi = {10.4995/var.2016.6319},

issn = {1989-9947},

year  = {2016},

date = {2016-11-01},

journal = {Virtual Archaeol. Rev.},

volume = {7},

number = {15},

pages = {54},

abstract = {textlessp class="VARAbstract"textgreaterThe ability of High Dynamic Range (HDR) imaging to capture the full range of lighting in a scene has meant that it is being increasingly used for Cultural Heritage (CH) applications. Photogrammetric techniques allow the semi-automatic production of 3D models from a sequence of images. Current photogrammetric methods are not always effective in reconstructing images under harsh lighting conditions, as significant geometric details may not have been captured accurately within under- and over-exposed regions of the image. HDR imaging offers the possibility to overcome this limitation, however the HDR images need to be tone mapped before they can be used within existing photogrammetric algorithms. In this paper we evaluate four different HDR tone-mapping operators (TMOs) that have been used to convert raw HDR images into a format suitable for state-of-the-art algorithms, and in particular keypoint detection techniques. The evaluation criteria used are the number of keypoints, the number of valid matches achieved and the repeatability rate. The comparison considers two local and two global TMOs. HDR data from four CH sites were used: Kaisariani Monastery (Greece), Asinou Church (Cyprus), Ch\^{a}teau des Baux (France) and Buonconsiglio Castle (Italy).textless/ptextgreater},

keywords = {hdr, hdr tone-mapping, high dynamic range, Image-based 3D reconstruction, imaging, keypoint detection},

pubstate = {published},

tppubtype = {article}

}