This Technical Report presents a Data Analysis approach which on the fly, starting from multiple ... more This Technical Report presents a Data Analysis approach which on the fly, starting from multiple acoustic/optical range images, elaborates the acquired unknown object by mosaicing multiple single frame meshes. In the context of the European ARROV project, we developed a 3D reconstruction pipeline, which provides a 3D model of an underwater scene from a sequence of range data captured by an acoustic camera mounted on board a Remotely Operated Vehicle (ROV). Our approach works on line by building the 3D model while the range images arrive from ROV. The method combines the range images in a sequence by minimizing the workload of the rendering system.
This paper presents a general Surface Reconstruction framework which encapsulates the uncertainty... more This paper presents a general Surface Reconstruction framework which encapsulates the uncertainty of the sampled data, making no assumption on the shape of the surface to be reconstructed. Starting from the input points (either points clouds or multiple range images), an Estimated Existence Function (EEF) is built which models the space in which the desired surface could exist and, by the extraction of EEF critical points, the surface is reconstructed. The final goal is the development of a generic framework able to adapt the result to different kinds of additional information coming from multiple sensors.
The Geometry & Graphics Group (G3) has been active in the eld of computer graphics and geometric... more The Geometry & Graphics Group (G3) has been active in the eld of computer graphics and geometric modeling for many years. The research activity of the group focuses on techniques for representing, manipulating, visualizing and reasoning on spatial objects, such as complex 3D shapes and multidimensional scalar elds. Recently, the emphasis of the research has been on structural and geometric modeling of 3D shapes, terrains and volume data. The reference applications of the research are in geographic data processing, scienti c visualization, computer aided design and animation.
3D mosaicing consists in building a geometric representation, in the form of of an object or scen... more 3D mosaicing consists in building a geometric representation, in the form of of an object or scene, given a set of different views. The representation consists of a surface mesh made of triangles or quadrilaterals. We consider a specific version of this problem, where: input consists of a sequence of range images; and output must be produced on-line, i.e., by building the mosaic frame by frame, through updates that are performed as each new frame comes. We report on existing methods that can be applied to this scenario, by focusing on the problem of building the mesh given the sequence of registered images. We do not report on methods for range image registration, which is regarded as a pre-processing here.
Abstract This paper presents a system for the 3D reconstruction of an underwater environment on t... more Abstract This paper presents a system for the 3D reconstruction of an underwater environment on the basis of multiple range views from an acoustical camera. The challenge is to provide the reconstruction on-line, as the range views are obtained from the sensor. The final target of the work is to improve the understanding of a human operator driving an underwater remotely operated vehicle (ROV). The acoustic camera provides a sequence of 3D images in real time (about 5 fps in the current version).
... C is called a lower set if 8c0 2 C0, 8c c0 then c 2 C0. For any c 2 C, the set Cc = fc0 2Cjc0... more ... C is called a lower set if 8c0 2 C0, 8c c0 then c 2 C0. For any c 2 C, the set Cc = fc0 2Cjc0 cg is the smallest lower set containing c, and it is called the down-closure of c. We also de ne the sub-closure of c as Cc = fc0 2Cjc0 < cg= Cc nfcg. ...
This article describes a new hierarchical model for representing a terrain. The model, called a H... more This article describes a new hierarchical model for representing a terrain. The model, called a Hierarchical Triangulated Irregular Network (HTIN), is a method for compression of spatial data and representation of a topographic surface at successively finer levels of detail. A HTIN is a hierarchy of triangle-based surface approximations, where each node, except for the root, is a triangulated irregular network refining a triangle face belonging to its parent in the hierarchy. In this paper we present an encoding structure for a HTIN and we describe an algorithm for its construction.
Generic drawings containing regions with holes and dangling chains (line features) are considered... more Generic drawings containing regions with holes and dangling chains (line features) are considered. An edge-junction graph description of a drawing is assumed as input obtained from earlier processing. A topological data structure is constructed that encodes also all regions, expressed in terms of the loops bounding them, and of the line features they contain, as well as topological relations (adjacency and incidence) between lines and regions. A practical algorithm is proposed, which builds such a topological representation in optimal O(n log n) time, where n is the number of edges in the drawing. (~) 1997 Elsevier Science B.V.
A technique for segmenting and reconstructing range images of polyhedral objects is presented. A ... more A technique for segmenting and reconstructing range images of polyhedral objects is presented. A piecewise-linear approximation based on a triangulation of the image is computed rst. Optimization techniques are applied next to detect jump and crease edges, to eliminate false boundaries, and to merge nearly coplanar triangles into larger polygonal patches.
Proceedings of the 1993 ACM/IEEE conference on Supercomputing - Supercomputing '93, 1993
Page 1. A Data-parallel Algorithm for Three-dimensional Delaunay Triangulation and its Implementa... more Page 1. A Data-parallel Algorithm for Three-dimensional Delaunay Triangulation and its Implementation Y. Ansel Teng * Francis Sullivan t Isabel Beichl $ Enrico Puppo ~ Abstract In this paper, we present a parallel algorithm for ...
In this chapter we discuss issues about Level Of Detail (LOD) representations for digital terrain... more In this chapter we discuss issues about Level Of Detail (LOD) representations for digital terrain models and, especially, we describe how to deal with very large terrain datasets through out-of-core techniques that explicitly manage I/O operations between levels of memory. LOD modeling in the related context of geographical maps is discussed in Chapters 3 and 4.
Proceedings 15th International Conference on Pattern Recognition. ICPR-2000, 2000
This paper proposes a technique for the threedimensional reconstruction of an underwater environm... more This paper proposes a technique for the threedimensional reconstruction of an underwater environment from multiple range views. The final target of the work lies in improving the understanding of a human operator guiding an underwater remotely operated vehicle (ROV) equipped with an acoustic camera, which provides a sequence of 3D images in real time. Since the field of view is narrow, we devise a technique for the reconstruction of relevant information of the image sequence up to build a mosaic of the surrounding scene. Due to the very noisy nature of the data and the low range resolution, smoothing, segmentation, registration, and fusion problems have been tackled. Examples on real images have been presented to show the promising performances of the algorithm.
International Journal of Computational Geometry & Applications, 1997
The best known output-sensitive sequential algorithm for computing the viewshed on a polyhedral t... more The best known output-sensitive sequential algorithm for computing the viewshed on a polyhedral terrain from a given viewpoint was proposed by Katz, Overmars, and Sharir 10 , and achieves time complexity O((k + n (n)) log n) where n and k are the input and output sizes respectively, and () is the inverse Ackermann's function. In this paper, we present a parallel algorithm that is based on the work mentioned above, and achieves O(log 2 n) time complexity, with work complexity O((k + n (n)) log n) in a CREW PRAM model. This improves on previous parallel complexity while maintaining work e ciency with respect to the best sequential complexity known.
A comprehensive study of multiresolution decompositions of planar domains into triangles is given... more A comprehensive study of multiresolution decompositions of planar domains into triangles is given. A model introduced that is more general than other multiresolution models proposed in the literature. The model is based on a collection of fragments of plane triangulations arranged into a partially ordered set. Di erent decompositions of a domain can be obtained by combining di erent fragments from the model. Theoretical results on the expressive power of such a model are given. An e cient algorithm is proposed that can extract a triangulation from the model, whose level of detail is variable over the domain according to a given threshold function. The algorithm works in linear time, and the extracted representation has minimum size among all possible triangulations that can be built from triangles in the model, and that satisfy the given level of detail. Major applications of these results are in real time rendering of complex surfaces, such as topographic surfaces ight simulation.
We introduce RGB triangulations, an extension of red-green triangulations that can support select... more We introduce RGB triangulations, an extension of red-green triangulations that can support selective refinement over subdivision meshes generated through quadrisection of triangles. Our purpose is to define a mechanism based on local operators that act on subdivision meshes while supporting operations similar to those available in Continuous Level Of Detail models. Our mechanism permits to take an adaptive mesh at intermediate level of subdivision and process it through both refinement and coarsening operations, by remaining consistent with an underlying Loop subdivision scheme. Our method does not require any hierarchical data structure, being based just on color codes and level numbers assigned to elements of a mesh, which can be encoded in a standard topological data structure with a small overhead.
... DAVID MOUNT Department of Computer Science, University of Maryland College Park, MD 20742, US... more ... DAVID MOUNT Department of Computer Science, University of Maryland College Park, MD 20742, USA ... 2. Preliminaries A polyhedral terrain T is the graph of a piecewise linear continuous function z = f(x; y) de ned over the X-Y plane. ...
This Technical Report presents a Data Analysis approach which on the fly, starting from multiple ... more This Technical Report presents a Data Analysis approach which on the fly, starting from multiple acoustic/optical range images, elaborates the acquired unknown object by mosaicing multiple single frame meshes. In the context of the European ARROV project, we developed a 3D reconstruction pipeline, which provides a 3D model of an underwater scene from a sequence of range data captured by an acoustic camera mounted on board a Remotely Operated Vehicle (ROV). Our approach works on line by building the 3D model while the range images arrive from ROV. The method combines the range images in a sequence by minimizing the workload of the rendering system.
This paper presents a general Surface Reconstruction framework which encapsulates the uncertainty... more This paper presents a general Surface Reconstruction framework which encapsulates the uncertainty of the sampled data, making no assumption on the shape of the surface to be reconstructed. Starting from the input points (either points clouds or multiple range images), an Estimated Existence Function (EEF) is built which models the space in which the desired surface could exist and, by the extraction of EEF critical points, the surface is reconstructed. The final goal is the development of a generic framework able to adapt the result to different kinds of additional information coming from multiple sensors.
The Geometry & Graphics Group (G3) has been active in the eld of computer graphics and geometric... more The Geometry & Graphics Group (G3) has been active in the eld of computer graphics and geometric modeling for many years. The research activity of the group focuses on techniques for representing, manipulating, visualizing and reasoning on spatial objects, such as complex 3D shapes and multidimensional scalar elds. Recently, the emphasis of the research has been on structural and geometric modeling of 3D shapes, terrains and volume data. The reference applications of the research are in geographic data processing, scienti c visualization, computer aided design and animation.
3D mosaicing consists in building a geometric representation, in the form of of an object or scen... more 3D mosaicing consists in building a geometric representation, in the form of of an object or scene, given a set of different views. The representation consists of a surface mesh made of triangles or quadrilaterals. We consider a specific version of this problem, where: input consists of a sequence of range images; and output must be produced on-line, i.e., by building the mosaic frame by frame, through updates that are performed as each new frame comes. We report on existing methods that can be applied to this scenario, by focusing on the problem of building the mesh given the sequence of registered images. We do not report on methods for range image registration, which is regarded as a pre-processing here.
Abstract This paper presents a system for the 3D reconstruction of an underwater environment on t... more Abstract This paper presents a system for the 3D reconstruction of an underwater environment on the basis of multiple range views from an acoustical camera. The challenge is to provide the reconstruction on-line, as the range views are obtained from the sensor. The final target of the work is to improve the understanding of a human operator driving an underwater remotely operated vehicle (ROV). The acoustic camera provides a sequence of 3D images in real time (about 5 fps in the current version).
... C is called a lower set if 8c0 2 C0, 8c c0 then c 2 C0. For any c 2 C, the set Cc = fc0 2Cjc0... more ... C is called a lower set if 8c0 2 C0, 8c c0 then c 2 C0. For any c 2 C, the set Cc = fc0 2Cjc0 cg is the smallest lower set containing c, and it is called the down-closure of c. We also de ne the sub-closure of c as Cc = fc0 2Cjc0 < cg= Cc nfcg. ...
This article describes a new hierarchical model for representing a terrain. The model, called a H... more This article describes a new hierarchical model for representing a terrain. The model, called a Hierarchical Triangulated Irregular Network (HTIN), is a method for compression of spatial data and representation of a topographic surface at successively finer levels of detail. A HTIN is a hierarchy of triangle-based surface approximations, where each node, except for the root, is a triangulated irregular network refining a triangle face belonging to its parent in the hierarchy. In this paper we present an encoding structure for a HTIN and we describe an algorithm for its construction.
Generic drawings containing regions with holes and dangling chains (line features) are considered... more Generic drawings containing regions with holes and dangling chains (line features) are considered. An edge-junction graph description of a drawing is assumed as input obtained from earlier processing. A topological data structure is constructed that encodes also all regions, expressed in terms of the loops bounding them, and of the line features they contain, as well as topological relations (adjacency and incidence) between lines and regions. A practical algorithm is proposed, which builds such a topological representation in optimal O(n log n) time, where n is the number of edges in the drawing. (~) 1997 Elsevier Science B.V.
A technique for segmenting and reconstructing range images of polyhedral objects is presented. A ... more A technique for segmenting and reconstructing range images of polyhedral objects is presented. A piecewise-linear approximation based on a triangulation of the image is computed rst. Optimization techniques are applied next to detect jump and crease edges, to eliminate false boundaries, and to merge nearly coplanar triangles into larger polygonal patches.
Proceedings of the 1993 ACM/IEEE conference on Supercomputing - Supercomputing '93, 1993
Page 1. A Data-parallel Algorithm for Three-dimensional Delaunay Triangulation and its Implementa... more Page 1. A Data-parallel Algorithm for Three-dimensional Delaunay Triangulation and its Implementation Y. Ansel Teng * Francis Sullivan t Isabel Beichl $ Enrico Puppo ~ Abstract In this paper, we present a parallel algorithm for ...
In this chapter we discuss issues about Level Of Detail (LOD) representations for digital terrain... more In this chapter we discuss issues about Level Of Detail (LOD) representations for digital terrain models and, especially, we describe how to deal with very large terrain datasets through out-of-core techniques that explicitly manage I/O operations between levels of memory. LOD modeling in the related context of geographical maps is discussed in Chapters 3 and 4.
Proceedings 15th International Conference on Pattern Recognition. ICPR-2000, 2000
This paper proposes a technique for the threedimensional reconstruction of an underwater environm... more This paper proposes a technique for the threedimensional reconstruction of an underwater environment from multiple range views. The final target of the work lies in improving the understanding of a human operator guiding an underwater remotely operated vehicle (ROV) equipped with an acoustic camera, which provides a sequence of 3D images in real time. Since the field of view is narrow, we devise a technique for the reconstruction of relevant information of the image sequence up to build a mosaic of the surrounding scene. Due to the very noisy nature of the data and the low range resolution, smoothing, segmentation, registration, and fusion problems have been tackled. Examples on real images have been presented to show the promising performances of the algorithm.
International Journal of Computational Geometry & Applications, 1997
The best known output-sensitive sequential algorithm for computing the viewshed on a polyhedral t... more The best known output-sensitive sequential algorithm for computing the viewshed on a polyhedral terrain from a given viewpoint was proposed by Katz, Overmars, and Sharir 10 , and achieves time complexity O((k + n (n)) log n) where n and k are the input and output sizes respectively, and () is the inverse Ackermann's function. In this paper, we present a parallel algorithm that is based on the work mentioned above, and achieves O(log 2 n) time complexity, with work complexity O((k + n (n)) log n) in a CREW PRAM model. This improves on previous parallel complexity while maintaining work e ciency with respect to the best sequential complexity known.
A comprehensive study of multiresolution decompositions of planar domains into triangles is given... more A comprehensive study of multiresolution decompositions of planar domains into triangles is given. A model introduced that is more general than other multiresolution models proposed in the literature. The model is based on a collection of fragments of plane triangulations arranged into a partially ordered set. Di erent decompositions of a domain can be obtained by combining di erent fragments from the model. Theoretical results on the expressive power of such a model are given. An e cient algorithm is proposed that can extract a triangulation from the model, whose level of detail is variable over the domain according to a given threshold function. The algorithm works in linear time, and the extracted representation has minimum size among all possible triangulations that can be built from triangles in the model, and that satisfy the given level of detail. Major applications of these results are in real time rendering of complex surfaces, such as topographic surfaces ight simulation.
We introduce RGB triangulations, an extension of red-green triangulations that can support select... more We introduce RGB triangulations, an extension of red-green triangulations that can support selective refinement over subdivision meshes generated through quadrisection of triangles. Our purpose is to define a mechanism based on local operators that act on subdivision meshes while supporting operations similar to those available in Continuous Level Of Detail models. Our mechanism permits to take an adaptive mesh at intermediate level of subdivision and process it through both refinement and coarsening operations, by remaining consistent with an underlying Loop subdivision scheme. Our method does not require any hierarchical data structure, being based just on color codes and level numbers assigned to elements of a mesh, which can be encoded in a standard topological data structure with a small overhead.
... DAVID MOUNT Department of Computer Science, University of Maryland College Park, MD 20742, US... more ... DAVID MOUNT Department of Computer Science, University of Maryland College Park, MD 20742, USA ... 2. Preliminaries A polyhedral terrain T is the graph of a piecewise linear continuous function z = f(x; y) de ned over the X-Y plane. ...
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Papers by Enrico Puppo
scalar elds. Recently, the emphasis of the research has been on structural and geometric modeling of 3D shapes, terrains and volume data. The reference applications of the research are in geographic data processing, scienti c visualization, computer aided design and animation.
scalar elds. Recently, the emphasis of the research has been on structural and geometric modeling of 3D shapes, terrains and volume data. The reference applications of the research are in geographic data processing, scienti c visualization, computer aided design and animation.