3D Object Matching and Reconstruction

	3D Object Repair Using 2D Algorithms P. Stavrou, P. Mavridis, G. Papaioannou, G. Passalis, T. Theoharis, Proc. 5th International Workshop on Computer Graphics and Geometric Modeling (CGGM 2006), Lecture Notes in Computer Science, 2006, Volume 3992, Computational Science – ICCS 2006, pp. 271-278. Abstract. A number of three-dimensional algorithms have been proposed to solve the problem of patching surfaces to rectify and extrapolate missing information due to model problems or bad geometry visibility during data capture. On the other hand, a number of similar yet more simple and robust techniques apply to 2D image data and are used for texture restoration. In this paper we make an attempt to bring these two-dimensional techniques to the 3D domain due to their obvious advantage of simplicity and controllability. Creating a depth image with the help of a voxelisation algorithm will allow us to apply a variety of image repair algorithms in order to mend a 3D object. The use of three variations of the texture synthesis algorithm is investigated. Constrained texture synthesis and its variations using the Haar wavelet and image decomposition methods are also proposed in order to preserve patterns appearing on the object while trying to maintain its geometry intact. Downloads: the paper Reference: BibTex doi:10.1007/11758525_36

	Efficient 3D Object Retrieval Using Depth Images N. Vajramushti, I. A. Kakadiaris, T. Theoharis, G. Papaioannou, 6th ACM SIGMM International Workshop on Multimedia Information Retrieval (ACM SIGMM MIR '04), New York, USA, pp. 189-196, 2004. Abstract. In this paper, we present a new three-dimensional object retrieval method. This method employs depth buffers for representing and comparing the objects. Specifically, multiple depth buffers per object (computed from different points of view) are compared for surface and volume similarity. Our method is easily extensible for hierarchical comparisons at multiple resolutions and is highly parallelizable. We have employed this method for both inter-class and intra-class retrieval tasks on a gallery of over 3 000 three-dimensional objects of vehicles with very encouraging results. The accuracy of the method depends on the number of depth buffers and the depth buffer resolution. Downloads: the paper Reference: BibTex doi:10.1145/1026711.1026743

	On the Automatic Assemblage of Arbitrary Broken Solid Artefacts G. Papaioannou, E. A. Karabassi, Elsevier, 21(5), pp. 401-412, 2003. Abstract. Presented here is a fast method that combines curve matching techniques with a surface matching algorithm to estimate the positioning and respective matching error for the joining of three-dimensional fragmented objects. Furthermore, this paper describes how multiple joints are evaluated and how the broken artefacts are clustered and transformed to form potential solutions of the assemblage problem. Downloads: the paper Reference: BibTex doi:10.1016/S0262-8856(03)00008-8

	Fast Fragment Assemblage Using Boundary Line and Surface Matching G. Papaioannou, T. Theoharis, Proc. IEEE/CVPR Workshop on Applications of Computer Vision in Archaeology (ACVA), 2003. Abstract. In the recent past, fragment matching has been treated in two different approaches, one using curve matching methods and one that compares whole surfaces or volumes, depending on the nature of the broken artefacts. Presented here is a fast, unified method that combines curve matching techniques with a surface matching algorithm to estimate the positioning and respective matching error for the joining of three-dimensional fragmented objects. Combining both aspects of fragment matching, essentially eliminates most of the ambiguities present in each one of the matching problem categories and helps provide more accurate results with low computational cost. Downloads: the paper Reference: BibTex

	Reconstruction of Three-dimensional Objects through Matching of their Parts G. Papaioannou, E.A. Karabassi, T. Theoharis, IEEE Transactions on Pattern Analysis and Machine Intelligence, 24(1), pp.114-124, 2002. Abstract. The problem of reassembling an object from its parts or fragments has never been addressed with a unified computational approach, which depends on the pure geometric form of the parts and not application-specific features. We propose a method for the automatic reconstruction of a model based on the geometry of its parts, which may be computer-generated models or range-scanned models. The matching process can benefit from any other external constraint imposed by the specific application. Downloads: the paper Reference: BibTex

	Virtual Archaeologist: Assembling the Past G. Papaioannou, E.A. Karabassi, T. Theoharis, IEEE Computer Graphics and Applications, 21(2), pp. 53-59, 2001. Abstract. This article describes a semi-automatic system for the reconstruction of archaeological finds from their fragments. Virtual Archaeologist is a system that uses computer graphics to calculate a measure of complementary matching between scanned data and employs optimization algorithms in order to estimate the correct relative pose between fragments and cluster those fragments that belong to the same entity. Downloads: the paper Reference: BibTex

	Segmentation and Surface Characterization of Arbitrary 3D Meshes for Object Reconstruction and Recognition G. Papaioannou, E.A. Karabassi, T. Theoharis, Proc. International Conference on Pattern Recognition ‘2000, IEEE, 2000, pp. 734-737. Abstract. Polygonal models are the most common representation of structured 3D data in computer graphics, pattern recognition and machine vision. The method presented here automatically identifies and labels all compact surface regions of a polygonal mesh, visible or not, and extracts valuable invariant features regarding their geometric attributes. A method that is independent of the mesh topology is also presented for the surface bumpiness estimation and the identification of coarse surface regions. Downloads: the paper Reference: BibTex

	Automatic Reconstruction of Archaeological Finds – A Graphics Approach G. Papaioannou, E.A. Karabassi, T. Theoharis, Proc. 4th International Conference on Computer Graphics and Artificial Intelligence (3IA' 2000), Limoges, France, pp117-125, 2000. Abstract. Reconstruction of archaeological finds from fragments, is a tedious task requiring many hours of work from the archaeologists and restoration personnel. Up to now, computers have significantly simplified this work by providing tools for the data encoding, storage, classification and visualisation in some cases. In this paper we go one step further by presenting a semi-automatic procedure for the full reconstruction of the original objects using computer graphics and artificial intelligence algorithms on geometrical information. Downloads: the paper Reference: BibTex

	Automatic Reconstruction of Objects from their Parts and its Application to Digital Archaeology G. Papaioannou, Ph.D. Dissertation (in Greek), Department of Informatics and Telecommunications, National and Kapodestrian University of Athens, 2001. Abstract. In this PhD thesis, a general computational method for the automatic reconstruction and assemblage of three-dimensional objects from parts or fragments was proposed and developed. This reconstruction problem may be regarded as a generalization of the jigsaw puzzle, where the number and shape of the pieces are unknown and some parts may be missing or damaged. The above problem arises mostly in archaeological reconstruction and restoration nut also in other scientific fields. The proposed method operates on the of digitized part models, estimates a measure of the complementary fitting between different pieces and forms clusters of these (properly aligned) models that represent the final reconstructed entities. The method relies on the geometry of the digitized data to solve the problem. However, additional available information, such as material attributes or structural details or patterns can improve both the method's performance and the quality of the results. The matching and data analysis algorithms used take advantage of graphics hardware to achieve high performance and combine techniques from the computer graphics, pattern analysis and optimization theory fields. Downloads: the Ph.D. dissertation (in Greek)