{"title":"Shape Segmentation and Matching from Noisy Point Clouds","authors":"T. Dey, Joachim Giesen, S. Goswami","doi":"10.2312/SPBG/SPBG04/193-199","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/193-199","url":null,"abstract":"We present the implementation results of a shape segmentation technique and an associated shape matching method whose input is a point sample from the shape. The sample is allowed to be noisy in the sense that they may scatter around the boundary of the shape instead of lying exactly on it. The algorithm is simple and mostly combinatorial in that it builds a single data structure, the Delaunay triangulation of the point set, and groups the tetrahedra to form the segments. A small set of weighted points are derived from the segments which are used as signatures to match shapes. Experimental results establish the effectiveness of the method in practice.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128463598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Stratified Point Sampling of 3D Models","authors":"Diego F. Nehab, Philip Shilane","doi":"10.2312/SPBG/SPBG04/049-056","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/049-056","url":null,"abstract":"Point sampling is an important intermediate step for a variety of computer graphics applications, and specialized sampling strategies have been developed to satisfy the requirements of each problem. In this article, we present a technique to generate a stratified sampling of 3D models that is applicable across many domains. The algorithm voxelizes the model and selects one sample per voxel, restricted to the original model's surface. Parameters allow control of the uniformity of the sample placement and the minimum distance between samples. We demonstrate the effectiveness of this technique in selecting stroke locations for painterly rendering models and for producing sampled geometry used as input to shape descriptors.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128697376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Topological estimation using witness complexes","authors":"V. Silva, G. Carlsson","doi":"10.2312/SPBG/SPBG04/157-166","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/157-166","url":null,"abstract":"This paper tackles the problem of computing topological invariants of geometric objects in a robust manner, using only point cloud data sampled from the object. It is now widely recognised that this kind of topological analysis can give qualitative information about data sets which is not readily available by other means. In particular, it can be an aid to visualisation of high dimensional data. Standard simplicial complexes for approximating the topological type of the underlying space (such as Cech, Rips, or a-shape) produce simplicial complexes whose vertex set has the same size as the underlying set of point cloud data. Such constructions are sometimes still tractable, but are wasteful (of computing resources) since the homotopy types of the underlying objects are generally realisable on much smaller vertex sets. We obtain smaller complexes by choosing a set of 'landmark' points from our data set, and then constructing a \"witness complex\" on this set using ideas motivated by the usual Delaunay complex in Euclidean space. The key idea is that the remaining (non-landmark) data points are used as witnesses to the existence of edges or simplices spanned by combinations of landmark points. \u0000 \u0000Our construction generalises the topology-preserving graphs of Martinetz and Schulten [MS94] in two directions. First, it produces a simplicial complex rather than a graph. Secondly it actually produces a nested family of simplicial complexes, which represent the data at different feature scales, suitable for calculating persistent homology [ELZ00, ZC04]. We find that in addition to the complexes being smaller, they also provide (in a precise sense) a better picture of the homology, with less noise, than the full scale constructions using all the data points. We illustrate the use of these complexes in qualitatively analyzing a data set of 3 × 3 pixel patches studied by David Mumford et al [LPM03].","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132410020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Proximity Graphs for Defining Surfaces over Point Clouds","authors":"Jan Klein, G. Zachmann","doi":"10.2312/SPBG/SPBG04/131-138","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/131-138","url":null,"abstract":"We present a new definition of an implicit surface over a noisy point cloud. It can be evaluated very fast, but, unlike other definitions based on the moving least squares approach, it does not suffer from artifacts. \u0000 \u0000In order to achieve robustness, we propose to use a different kernel function that approximates geodesic distances on the surface by utilizing a geometric proximity graph. The starting point in the graph is determined by approximate nearest neighbor search. From a variety of possibilities, we have examined the Delaunay graph and the sphere-of-influence graph (SIG). For both, we propose to use modifications, the r-SIG and the pruned Delaunay graph. \u0000 \u0000We have implemented our new surface definition as well as a test environment which allows to visualize and to evaluate the quality of the surfaces. We have evaluated the different surfaces induced by different proximity graphs. The results show that artifacts and the root mean square error are significantly reduced.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115313448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Points Reloaded: Point-Based Rendering Revisited","authors":"M. Sainz, R. Pajarola, R. Lario","doi":"10.2312/SPBG/SPBG04/121-128","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/121-128","url":null,"abstract":"The increasing popularity of points as rendering primitives has led to a variety of different rendering algorithms, and in particular the different implementations compare like apples to oranges. In this paper we revisit a number of recently developed point-based rendering implementations. We briefly summarize a few proposed hierarchical multiresolution point data structures and their advantages. Based on a common multiresolution framework we then describe and examine different hardware accelerated point rendering algorithms. Experimental results are given with respect to performance timing and rendering quality for the different approaches.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122908336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Point-based Surface Rendering with Motion Blur","authors":"Xin Guan, K. Mueller","doi":"10.2312/SPBG/SPBG04/033-040","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/033-040","url":null,"abstract":"In this paper we show how to extend point-based surface rendering to illustrate object motion. We do this by first extruding the circular points into ellipsoids, which fill the space traced out by the points in motion. Using ellipsoids instead of cylinders achieves a low-passing effect of the motion trail. We then find the screen-space projection of each ellipsoid, which is an ellipse. These can be rendered conveniently using hardware acceleration. Our technique thus facilitates the rendering of complex objects with real-time motion blur. It gives the viewer a sharply rendered object together with the hint of the direction of motion. The construction of the motion blur trails can be based on different rendering primitives, as is also discussed in the paper. Various trail textures are presented to achieve artistic rendering results.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128489947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Real-Time Point Cloud Refinement","authors":"Gaël Guennebaud, L. Barthe, M. Paulin","doi":"10.2312/SPBG/SPBG04/041-048","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/041-048","url":null,"abstract":"Splatting-based rendering techniques are currently the best choice for efficient high quality rendering of pointbased geometries. However, such techniques are not suitable for large magnification, especially when the object is under-sampled. This paper improves the rendering quality of pure splatting techniques using a fast dynamic up-sampling algorithm for point-based geometry. Our algorithm is inspired by interpolatory subdivision surfaces where the geometry is refined iteratively. At each step the refined geometry is that from the previous step enriched by a new set of points. The point insertion procedure uses three operators: a local neighborhood selection operator, a refinement operator (adding new points) and a smoothing operator. Even though our insertion procedure makes the analysis of the limit surface complicated and it does not guarantee its G1 continuity, it remains very efficient for high quality real-time point rendering. Indeed, while providing an increased rendering quality, especially for large magnification, our algorithm needs no other preprocessing nor any additional information beyond that used by any splatting technique.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"411 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115937002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Normals and Projection Operators for Surfaces Defined by Point Sets","authors":"M. Alexa, A. Adamson","doi":"10.2312/SPBG/SPBG04/149-155","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/149-155","url":null,"abstract":"Levin's MLS projection operator allows defining a surface from a set of points and represents a versatile procedure to generate points on this surface. Practical problems of MLS surfaces are a complicated non-linear optimization to compute a tangent frame and the (commonly overlooked) fact that the normal to this tangent frame is not the surface normal. An alternative definition of Point Set Surfaces, inspired by the MLS projection, is the implicit surface version of Adamson & Alexa.We use this surface definition to show how to compute exact surface normals and present simple, efficient projection operators. The exact normal computation also allows computing orthogonal projections.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122771948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mattias Andersson, Joachim Giesen, M. Pauly, B. Speckmann
{"title":"Bounds on the k-Neighborhood for Locally Uniformly Sampled Surfaces","authors":"Mattias Andersson, Joachim Giesen, M. Pauly, B. Speckmann","doi":"10.2312/SPBG/SPBG04/167-171","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/167-171","url":null,"abstract":"Given a locally uniform sample set P of a smooth surface S. We derive upper and lower bounds on the number k of nearest neighbors of a sample point p that have to be chosen from P such that this neighborhood contains all restricted Delaunay neighbors of p. In contrast to the trivial lower bound, the upper bound indicates that a sampling condition that is used in many computational geometry proofs is quite reasonable from a practical point of view.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"215 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116389481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Layered Point Clouds","authors":"E. Gobbetti, F. Marton","doi":"10.2312/SPBG/SPBG04/113-120","DOIUrl":"https://doi.org/10.2312/SPBG/SPBG04/113-120","url":null,"abstract":"We present a simple point-based multiresolution structure for interactive visualization of very large point sampled models on consumer graphics platforms. The structure is based on a hierarchy of precomputed object-space point clouds. At rendering time, the clouds are combined coarse-to-fine with a top-down structure traversal to locally adapt sample densities according to the projected size in the image. Since each cloud is made of a few thousands of samples, the multiresolution extraction cost is amortized over many graphics primitives, and host-to-graphics communication effectively exploits on-board caching and object based rendering APIs. The progressive block based refinement nature of the rendering traversal is well suited to hiding out-of-core data access latency, and lends itself well to incorporate backface, view frustum, and occlusion culling, as well as compression and viewdependent progressive transmission. The resulting system allows rendering of complex models at high frame rates (over 60M splat/second), supports network streaming, and is fundamentally simple to implement.","PeriodicalId":136739,"journal":{"name":"Symposium on Point Based Graphics","volume":"452 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122799568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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