2022 |
Betsas, Thodoris; Georgopoulos, Andreas Point-Cloud Segmentation for 3D Edge Detection and Vectorization Journal Article In: Heritage, vol. 5, no. 4, pp. 4037–4060, 2022, ISSN: 2571-9408, (Number: 4 Publisher: Multidisciplinary Digital Publishing Institute). Abstract | Links | BibTeX | Tags: 3D computer vision, Cultural heritage, Edge detection, Photogrammetry, point-cloud segmentation, SfM-MVS @article{betsas_point-cloud_2022,The creation of 2D–3D architectural vector drawings constitutes a manual, labor-intensive process. The scientific community has not provided an automated approach for the production of 2D–3D 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–Multi 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. |
Shabani, Amirhosein; Skamantzari, Margarita; Tapinaki, Sevasti; Georgopoulos, Andreas; Plevris, Vagelis; Kioumarsi, Mahdi 3D simulation models for developing digital twins of heritage structures: challenges and strategies Journal Article In: Procedia Structural Integrity, vol. 37, pp. 314-320, 2022, ISSN: 2452-3216, (ICSI 2021 The 4th International Conference on Structural Integrity). Abstract | Links | BibTeX | Tags: 3D geometric documentation, 3D laser scanner, Cultural heritage, Digital twins, Finite element model, Photogrammetry @article{SHABANI2022314,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. |
2021 |
Kolokoussis, P; Skamantzari, M; Tapinaki, S; Karathanassi, V; Georgopoulos, A 3D AND HYPERSPECTRAL DATA INTEGRATION FOR ASSESSING MATERIAL DEGRADATION IN MEDIEVAL MASONRY HERITAGE BUILDINGS Journal Article In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XLIII-B2-2021, pp. 583–590, 2021. Links | BibTeX | Tags: 3D reconstruction, Cultural heritage, Hyperspectral Images, Material Analysis, Photogrammetry @article{isprs-archives-XLIII-B2-2021-583-2021, |
Chroni, Athina; Georgopoulos, Andreas In: pp. 78–89, Springer, Cham, 2021, ISBN: 978-3-030-73043-7. Abstract | Links | BibTeX | Tags: 3D modelling, Cultural heritage, Digitization, Documentation, G.I.S., Intangible, Ioannina, Open sources, Photogrammetry, Tangible @incollection{Chroni2021,The specific paper forms part of the Postdoctoral Research Project focusing on Ioannina city’s Ottoman period (1430-1913) and its multicultural profile as depicted in buildings, public or private, religious or secular, conventional or more elaborate, each having its own historical and architectural interest. Unfortunately, most of the landmark buildings have been destroyed due to natural disasters, religious hatred and the unbridled, often uncontrolled modern constructions. However, the existence and form of several of those edifices survived thanks to fragmentary information of various kinds, while their position in the urban web and their dimensions can be clarified, in several cases, by their comparative studies with buildings recorded at the same representations whose location and dimensions are known or buildings preserved until today. Under this perspective, a variety of data like historiographic, bibliographic, archaeological, cartographic, topographic, remote sensing imagery, optical displays, travelers’ descriptions, other literary sources, local legends, inhabitants’ interviews have been collected, analyzed, cross-examined and digitally processed, thus leading to the development of a Geographic Information System, the 3-D landmarks digital models, a web data base and QR coding at the specific sites, where the landmark buildings used to stand, thus connecting the intangible (digital) with the tangible (physical space) and achieving interaction of the project with the local community. Moreover, cultural walks within the city's urban web, related to the project’s axis are also proposed. |
Boutsi, A -M; Verykokou, S; Soile, S; Ioannidis, C Α PATTERN-BASED AUGMENTED REALITY APPLICATION FOR THE DISSEMINATION OF CULTURAL HERITAGE Journal Article In: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. VIII-M-1-2021, pp. 57–63, 2021. Links | BibTeX | Tags: 3D modelling, Augmented Reality, Computer Vision, Cultural heritage, mobile app, Photogrammetry @article{isprs-annals-VIII-M-1-2021-57-2021, |
Ioannidis, Charalabos; Soile, Sofia; Boutsi, Argyro-maria; Verykokou, Styliani; Bourexis, Fotios; Potsiou, Chryssy From 3D documentation to XR representation of Cultural Heritage buildings -The case of the Katholikon of St. Stephen, Meteora Proceedings Article In: FIG e-Working Week 2021, Smart Surveyors for Land and Water Management, 2021. Abstract | Links | BibTeX | Tags: 3D modelling, AR, Cultural heritage, Photogrammetry, visualization, VR @inproceedings{Ioannidis2021,Photogrammetric surveying and 3D modelling are of immense value for the diagnosis and conservation of historic and religious buildings. In case they are coupled with eXtended Reality (XR) technologies (i.e., Virtual, Augmented and Mixed Reality), different levels of interpretation, interaction and dissemination can be achieved. This paper presents a holistic approach to the multi-representation of the restoration phases of a Byzantine church. The aim is twofold; the introduction of a low-cost photogrammetric methodology for a detailed and accurate 3D geometric documentation of CH buildings, and the development of a web-based integrated 3D platform with XR functionalities. The proposed methodology is applied to the external and internal 3D reconstruction of the 16 th century old church (Katholikon) of St. Stephen's Monastery in Meteora, Greece, at two different periods: prior and after church maintenance work and restoration innervations. Close-range photogrammetry and computer vision are used for the collection of image data and the generation of dense point clouds, surface models and texture mapping. The final 3D models along with their supported metadata are integrated into an online XR viewer for a comparative temporal analysis through an immersive experience. The viewer has the following capabilities: (i) automated virtual tour on the 3D scene, (ii) points of interest, (iii) VR navigation as well as, (iv) marker-less AR based on hand pattern recognition. The 3D rendering and progressive loading, the interactive tools as well as the various visualization modes are built upon Three.js, Tween.js and AR.js libraries. The evaluation of the developed platform regarding performance and usability demonstrates the effectiveness of VR and AR in remote access, monitoring and preservation of tangible Cultural Heritage. |
2020 |
Verykokou, Styliani; Ioannidis, Charalabos Exterior orientation estimation of oblique aerial images using SfM-based robust bundle adjustment Journal Article In: Int. J. Remote Sens., vol. 41, no. 18, pp. 7233–7270, 2020, ISSN: 0143-1161. Abstract | Links | BibTeX | Tags: aerial triangulation, exterior orientation, oblique aerial images, Photogrammetry, structure from motion @article{Verykokou2020,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 |
2019 |
Tapinaki, S; Skamantzari, M; Chliverou, R; Evgenikou, V; Konidi, A M; Ioannatou, E; Mylonas, A; Georgopoulos, A 3D IMAGE BASED GEOMETRIC DOCUMENTATION OF A MEDIEVAL FORTRESS Journal Article In: ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci., vol. XLII-2/W9, pp. 699–705, 2019, ISSN: 2194-9034. Abstract | Links | BibTeX | Tags: 3D model, laser scanning, Orthophoto, Photogrammetry, UAV @article{Tapinaki2019,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. |
2018 |
Menna, Fabio; Agrafiotis, Panagiotis; Georgopoulos, Andreas State of the art and applications in archaeological underwater 3D recording and mapping Miscellaneous 2018, ISSN: 12962074. Abstract | Links | BibTeX | Tags: 3D Recording and Mapping, LiDAR, Photogrammetry, Sonar, Underwater Archaeology @misc{Menna2018,Since remote times, mankind has been bound to water bodies and evidence of human life from the very beginning hides under the water level, off the coasts, under shallow seas or deep oceans, but also inland water bodies of countries all around the world. Recording, documenting and, ultimately, protecting underwater cultural heritage is an obligation of mankind and dictated by international treaties like the Convention on the Protection of the Underwater Cultural Heritage that fosters and encourages the use of “non-destructive techniques and survey methods in preference over the recovery of objects”. 3D digital surveying and mapping techniques represent an invaluable set of effective tools for reconnaissance, documentation, monitoring, but also public diffusion and awareness of underwater cultural heritage (UCH) assets. This paper presents an extensive review over the sensors and the methodologies used in archaeological underwater 3D recording and mapping together with relevant highlights of well renowned projects in 3D recording underwater. |
2017 |
Kouimtzoglou, T; Stathopoulou, E K; Agrafiotis, P; Georgopoulos, A Image-based 3D reconstruction data as an analysis and documentation tool for architects: The case of Plaka bridge in Greece Journal Article In: Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch., vol. 42, no. 2W3, pp. 391–397, 2017, ISSN: 16821750. Abstract | Links | BibTeX | Tags: Architecture, Cultural heritage, Image-based 3D reconstruction, Photogrammetry @article{Kouimtzoglou2017,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. |
Georgopoulos, Andreas; Stathopoulou, Elisavet Konstantina Data Acquisition for 3D Geometric Recording: State of the Art and Recent Innovations Book Section In: Vincent, Matthew L.; ópez-Menchero Bendicho, Víctor Manuel L; Ioannides, Marinos; Levy, Thomas E. (Ed.): Herit. Archaeol. Digit. Age Acquis. Curation, Dissem. Spat. Cult. Herit. Data, pp. 1–26, Springer International Publishing, Cham, 2017. Abstract | Links | BibTeX | Tags: 3D geometric recording, Depth sensors, Image-based 3D reconstruction, Photogrammetry, Scanning @incollection{Georgopoulos2017a,Digitization of Cultural Heritage assets and sites is a broad term that includes quantitative as well as qualitative data acquisition. Towards a holistic, complete documentation, as outlined by the Venice Charter (1964), capturing the geometry of an object is considered to be one of the first and most essential steps. Within the photogrammetric, the computer vision and the robotics communities, various techniques for 2D, 3D, even 4D data acquisition and digitization have been developed during the past years. Cultural heritage assets are still a challenging object due to the complexity of their shape, the variety of their types, the high requirements of accuracy, and the heterogeneity of the end-users. This chapter focuses on the state of the art of the geometric 3D data acquisition methods, classifying them generally into passive and active. For each category, the available sensors and their working principles are presented and criticized, followed by acquisition network design suggestions and implementation guidelines. In this way, the reader is presented with their merits and disadvantages in order to be able to decide for their correct implementation. |
Hatzopoulos, John N; Stefanakis, Dimitrios; Georgopoulos, Andreas; Tapinaki, Sevasti; Pantelis, Volonakis; Liritzis, Ioannis In: Mediterr. Archaeol. Archaeom., vol. 17, no. 3, pp. 311–336, 2017, ISSN: 22418121. Abstract | Links | BibTeX | Tags: Education, Game engine, Laser scanner, Monument mapping, Photogrammetry, Restoration, Surveying, UAS @article{Hatzopoulos2017,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. |
2022 |
Point-Cloud Segmentation for 3D Edge Detection and Vectorization Journal Article In: Heritage, vol. 5, no. 4, pp. 4037–4060, 2022, ISSN: 2571-9408, (Number: 4 Publisher: Multidisciplinary Digital Publishing Institute). |
3D simulation models for developing digital twins of heritage structures: challenges and strategies Journal Article In: Procedia Structural Integrity, vol. 37, pp. 314-320, 2022, ISSN: 2452-3216, (ICSI 2021 The 4th International Conference on Structural Integrity). |
2021 |
3D AND HYPERSPECTRAL DATA INTEGRATION FOR ASSESSING MATERIAL DEGRADATION IN MEDIEVAL MASONRY HERITAGE BUILDINGS Journal Article In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. XLIII-B2-2021, pp. 583–590, 2021. |
In: pp. 78–89, Springer, Cham, 2021, ISBN: 978-3-030-73043-7. |
Α PATTERN-BASED AUGMENTED REALITY APPLICATION FOR THE DISSEMINATION OF CULTURAL HERITAGE Journal Article In: ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. VIII-M-1-2021, pp. 57–63, 2021. |
From 3D documentation to XR representation of Cultural Heritage buildings -The case of the Katholikon of St. Stephen, Meteora Proceedings Article In: FIG e-Working Week 2021, Smart Surveyors for Land and Water Management, 2021. |
2020 |
Exterior orientation estimation of oblique aerial images using SfM-based robust bundle adjustment Journal Article In: Int. J. Remote Sens., vol. 41, no. 18, pp. 7233–7270, 2020, ISSN: 0143-1161. |
2019 |
3D IMAGE BASED GEOMETRIC DOCUMENTATION OF A MEDIEVAL FORTRESS Journal Article In: ISPRS - Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci., vol. XLII-2/W9, pp. 699–705, 2019, ISSN: 2194-9034. |
2018 |
State of the art and applications in archaeological underwater 3D recording and mapping Miscellaneous 2018, ISSN: 12962074. |
2017 |
Image-based 3D reconstruction data as an analysis and documentation tool for architects: The case of Plaka bridge in Greece Journal Article In: Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. - ISPRS Arch., vol. 42, no. 2W3, pp. 391–397, 2017, ISSN: 16821750. |
Data Acquisition for 3D Geometric Recording: State of the Art and Recent Innovations Book Section In: Vincent, Matthew L.; ópez-Menchero Bendicho, Víctor Manuel L; Ioannides, Marinos; Levy, Thomas E. (Ed.): Herit. Archaeol. Digit. Age Acquis. Curation, Dissem. Spat. Cult. Herit. Data, pp. 1–26, Springer International Publishing, Cham, 2017. |
In: Mediterr. Archaeol. Archaeom., vol. 17, no. 3, pp. 311–336, 2017, ISSN: 22418121. |