Symposium on Point Based Graphics 05
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High-Quality Surface Splatting on Today s GPUs
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Botsch, Mario
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Hornung, Alexander
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Zwicker, Matthias
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Kobbelt, Leif
Voronoi Rasterization of Sparse Point Sets
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Talton, Jerry O.
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Carr, Nathan A.
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Hart, John C.
Conformal Alpha Shapes
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Cazals, Frederic
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Giesen, Joachim
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Pauly, Mark
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Zomorodian, Afra
Normal Estimation for Point Clouds: A Comparison Study for a Voronoi Based Method
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Dey, Tamal K.
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Li, Gang
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Sun, Jian
Computing Variation Modes for Point Set Surfaces
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Miao, Lanfang
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Huang, Jin
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Liu, Xinguo
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Bao, Hujun
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Peng, Qunsheng
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Guo, Baining
A Practical Structured Light Acquisition System for Point-Based Geometry and Texture
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Sadlo, Filip
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Weyrich, Tim
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Peikert, Ronald
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Gross, Markus
Robust Filtering of Noisy Scattered Point Data
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Schall, Oliver
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Belyaev, Alexander
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Seidel, Hans-Peter
Surface Reconstruction with Enriched Reproducing Kernel Particle Approximation
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Reuter, Patrick
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Joyot, Pierre
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Trunzler, Jean
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Boubekeur, Tamy
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Schlick, Christophe
Point Sampling with Uniformly Distributed Lines
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Rovira, Jordi
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Wonka, Peter
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Castro, Francesc
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Sbert, Mateu
DUODECIM - A Structure for Point Scan Compression and Rendering
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Krüger, Jens
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Schneider, Jens
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Westermann, Rüdiger
Conversion of Point-Sampled Models to Textured Meshes
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Wicke, Martin
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Olibet, Sandro
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Gross, Markus
A Unified Lagrangian Approach to Solid-Fluid Animation
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Keiser, Richard
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Adams, Bart
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Gasser, Dominique
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Bazzi, Paolo
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Dutré, Philip
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Gross, Markus
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Recent Submissions
Item Interactive Ray Tracing of Point-based Models(The Eurographics Association, 2005) Wald, Ingo; Seidel, Hans-Peter; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerPoint-based methods have recently gained significant interest, as their simplicity and independence of connectivity make them a simple and powerful tool in both modelling and rendering. Still, their use for high-quality and photorealistic rendering is still in its infancy, in particular for interactive applications. This paper describes a framework for interactively ray tracing point-based models based on a combination of an implicit surface representation, an efficient surface intersection algorithm, and a specially designed acceleration structure. Using this framework allows for interactively ray tracing even highly complex models on a single PC, including global illumination effects and the interactive visualization of a 24-million-point model with ray traced shadows.Item High-Quality Surface Splatting on Today s GPUs(The Eurographics Association, 2005) Botsch, Mario; Hornung, Alexander; Zwicker, Matthias; Kobbelt, Leif; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerBecause of their conceptual simplicity and superior flexibility, point-based geometries evolved into a valuable alternative to surface representations based on polygonal meshes. Elliptical surface splats were shown to allow for high-quality anti-aliased rendering by sophisticated EWA filtering. Since the publication of the original software-based EWA splatting, several authors tried to map this technique to the GPU in order to exploit hardware acceleration. Due to the lacking support for splat primitives, these methods always have to find a trade-off between rendering quality and rendering performance. In this paper, we discuss the capabilities of today s GPUs for hardware-accelerated surface splatting. We present an approach that achieves a quality comparable to the original EWA splatting at a rate of more than 20M elliptical splats per second. In contrast to previous GPU renderers, our method provides per-pixel Phong shading even for dynamically changing geometries and high-quality anti-aliasing by employing a screen-space pre-filter in addition to the object-space reconstruction filter. The use of deferred shading techniques effectively avoids unnecessary shader computations and additionally provides a clear separation between the rasterization and the shading of elliptical splats, which considerably simplifies the development of custom shaders. We demonstrate quality, efficiency, and flexibility of our approach by showing several shaders on a range of models.Item Voronoi Rasterization of Sparse Point Sets(The Eurographics Association, 2005) Talton, Jerry O.; Carr, Nathan A.; Hart, John C.; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerPoint-based representations are becoming increasingly common in computer graphics, especially for visualizing data sets where the number of points is large relative to the number of pixels involved in their display. When dealing with sparse point sets, however, many traditional rendering algorithms for point data perform poorly, either by generating blurry or non-occluding surface representations or by requiring extensive pre-processing to yield good results. In this paper we present a novel method for point-based surface visualization that we call Voronoi rasterization. Voronoi rasterization uses modern programmable graphics hardware to generate occluding surface representations from sparse, oriented point sets without preprocessing. In particular, Voronoi rasterization clips away overlapping flaps between neighboring splats and generates an approximation of the Voronoi diagram of the points under the surface s geodesic distance. To approximate smooth shading and texturing on top of this clipped surface, our method uses existing techniques to construct a smoothly blended screen-space attribute field that implicitly accounts for neighborhood relations between points.Item Progressive Splatting(The Eurographics Association, 2005) Wu, Jianhua; Zhang, Zhuo; Kobbelt, Leif; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerSurface splatting enables high quality and efficient rendering algorithms for dense point-sampled datasets. However, with increasing data complexity, the need for multiresolution models becomes evident. For triangle meshes, progressive or continuous level of detail hierarchies have proven to be very effective when it comes to (locally) adapt the resolution level of the 3D model to the application-dependent quality requirements. In this paper we transfer this concept to splat-based geometry representations. Our progressive splat decimation procedure uses the standard greedy approach but unlike previous work, it uses the full splat geometry in the decimation criteria and error estimates, not just the splat centers. With two improved error metrics, this new greedy framework offers better approximation quality than other progressive splat decimators. It comes even close to the recently proposed globally optimized single-resolution sub-sampling techniques while being faster by a factor of 3.Item Conformal Alpha Shapes(The Eurographics Association, 2005) Cazals, Frederic; Giesen, Joachim; Pauly, Mark; Zomorodian, Afra; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerWe define a new filtration of the Delaunay triangulation of a finite set of points in Rd, similar to the alpha shape filtration. The new filtration is parameterized by a local scale parameter instead of the global scale parameter in alpha shapes. Since our approach shares many properties with the alpha shape filtration and the local scale parameter conforms to the local geometry we call it conformal alpha shape filtration. The local scale parameter is motivated from applications and previous algorithms in surface reconstruction. We show how conformal alpha shapes can be used for surface reconstruction of non-uniformly sampled surfaces, which is not possible with alpha shapes.Item Normal Estimation for Point Clouds: A Comparison Study for a Voronoi Based Method(The Eurographics Association, 2005) Dey, Tamal K.; Li, Gang; Sun, Jian; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerMany applications that process a point cloud data benefit from a reliable normal estimation step. Given a point cloud presumably sampled from an unknown surface, the problem is to estimate the normals of the surface at the data points. Two approaches, one based on numerical optimizations and another based on Voronoi diagrams are known for the problem. Variations of numerical approaches work well even when point clouds are contaminated with noise. Recently a variation of the Voronoi based method is proposed for noisy point clouds. The centrality of the normal estimation step in point cloud processing begs a thorough study of the two approaches so that one knows which approach is appropriate for what circumstances. This paper presents such results.Item A Sampling Theorem for MLS Surfaces(The Eurographics Association, 2005) Bremer, Peer-Timo; Hart, John C.; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerRecently, point set surfaces have been the focus of a large number of research efforts. Several different methods have been proposed to define surfaces from points and have been used in a variety of applications. However, so far little is know about the mathematical properties of the resulting surface. A central assumption for most algorithms is that the surface construction is well defined within a neighborhood of the samples. However, it is not clear that given an irregular sampling of a surface this is the case. The fundamental problem is that point based methods often use a weighted least squares fit of a plane to approximate a surface normal. If this minimization problem is ill-defined so is the surface construction. In this paper, we provide a proof that given reasonable sampling conditions the normal approximations are well defined within a neighborhood of the samples. Similar to methods in surface reconstruction, our sampling conditions are based on the local feature size and thus allow the sampling density to vary according to geometric complexity.Item Computing Variation Modes for Point Set Surfaces(The Eurographics Association, 2005) Miao, Lanfang; Huang, Jin; Liu, Xinguo; Bao, Hujun; Peng, Qunsheng; Guo, Baining; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerPoint sets have become a popular shape representation. In this paper, we present a novel approach to computing variation modes for point set surfaces, and represent the point set surface as a linear combination of the variation modes, called a generative representation for the point set surface. Given a point set, our approach consists of two steps: The first is to produce a set of new samples with increasing smoothness and less detailed features. We use a modified smoothing method based on moving least squares (MLS) surface to produce the samples. The second is to arrange the shape vectors of the new samples together with the original point set into a matrix, and then compute the singular value decomposition of the matrix, producing a set of variation modes (the eigen vectors). Using the variation modes and the generative representation, we can easily synthesize new shapes. Typical applications are low/high/band pass filtering as well as denoising and detail enhancement in multiple scales.Item A Practical Structured Light Acquisition System for Point-Based Geometry and Texture(The Eurographics Association, 2005) Sadlo, Filip; Weyrich, Tim; Peikert, Ronald; Gross, Markus; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerWe present a simple and high-quality 3D scanning system based on structured light. It uses the common setup of a video projector, a computer-controlled turntable and a single camera. Geometry is acquired using a combination of Gray code and phase-shift projections, and it is stored and processed in a point-based representation. We achieve high accuracy by careful calibration of camera, projector, and turntable axis. In addition, we make use of the projector's calibration and extend it to a calibrated light source, allowing for a simple reconstruction of material properties for each surface point. We alternatively use a Lambertian reflectance model, or fit a Phong reflectance model to the samples under different turntable orientations. The acquisition pipeline is entirely point-based, avoiding the need of triangulation during all processing stages.Item Robust Filtering of Noisy Scattered Point Data(The Eurographics Association, 2005) Schall, Oliver; Belyaev, Alexander; Seidel, Hans-Peter; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerIn this paper, we develop a method for robust filtering of a noisy set of points sampled from a smooth surface. The main idea of the method consists of using a kernel density estimation technique for point clustering. Specifically, we use a mean-shift based clustering procedure. With every point of the input data we associate a local likelihood measure capturing the probability that a 3D point is located on the sampled surface. The likelihood measure takes into account the normal directions estimated at the scattered points. Our filtering procedure suppresses noise of different amplitudes and allows for an easy detection of outliers which are then automatically removed by simple thresholding. The remaining set of maximum likelihood points delivers an accurate point-based approximation of the surface. We also show that while some established meshing techniques often fail to reconstruct the surface from original noisy point scattered data, they work well in conjunction with our filtering method.Item Surface Reconstruction with Enriched Reproducing Kernel Particle Approximation(The Eurographics Association, 2005) Reuter, Patrick; Joyot, Pierre; Trunzler, Jean; Boubekeur, Tamy; Schlick, Christophe; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerThere are many techniques that reconstruct continuous 3D surfaces from scattered point data coming from laser range scanners. One of the most commonly used representations are Point Set Surfaces (PSS) defined as the set of stationary points of a Moving Least Squares (MLS) projection operator. One interesting property of the MLS projection is to automatically filter out high frequency noise, that is usually present in raw data due to scanning errors. Unfortunately, the MLS projection also smoothes out any high frequency feature, such as creases or corners, that may be present in the scanned geometry, and does not offer any possibility to distinguish between such feature and noise. The main contribution of this paper, is to present an alternative projection operator for surface reconstruction, based on the Enriched Reproducing Kernel Particle Approximation (ERKPA), which allows the reconstruction process to account for high frequency features, by letting the user explicitly tag the corresponding areas of the scanned geometry.Item Point Sampling with Uniformly Distributed Lines(The Eurographics Association, 2005) Rovira, Jordi; Wonka, Peter; Castro, Francesc; Sbert, Mateu; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerIn this paper we address the problem of extracting representative point samples from polygonal models. The goal of such a sampling algorithm is to find points that are evenly distributed. We propose star-discrepancy as a measure for sampling quality and propose new sampling methods based on global line distributions. We investigate several line generation algorithms including an efficient hardware-based sampling method. Our method contributes to the area of point-based graphics by extracting points that are more evenly distributed than by sampling with current algorithms.Item DUODECIM - A Structure for Point Scan Compression and Rendering(The Eurographics Association, 2005) Krüger, Jens; Schneider, Jens; Westermann, Rüdiger; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerIn this paper we present a compression scheme for large point scans including per-point normals. For the encoding of such scans we introduce a particular type of closest sphere packing grids, the hexagonal close packing (HCP). HCP grids provide a structure for an optimal packing of 3D space, and for a given sampling error they result in a minimal number of cells if geometry is sampled into these grids. To compress the data, we extract linear sequences (runs) of filled cells in HCP grids. The problem of determining optimal runs is turned into a graph theoretical one. Point positions and normals in these runs are incrementally encoded. At a grid spacing close to the point sampling distance, the compression scheme only requires slightly more than 3 bits per point position. Incrementally encoded per-point normals are quantized at high fidelity using only 5 bits per normal (see Figure 1). The compressed data stream can be decoded in the graphics processing unit (GPU). Decoded point positions are saved in graphics memory, and they are then used on the GPU again to render point primitives. In this way we render gigantic point scans from their compressed representation in local GPU memory at interactive frame rates (see Figure 2).Item Conversion of Point-Sampled Models to Textured Meshes(The Eurographics Association, 2005) Wicke, Martin; Olibet, Sandro; Gross, Markus; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerWe present an algorithm to convert point-sampled objects to textured meshes. The output mesh carries the geometric information present in the input model, while information about color and other surface attributes is separated and stored in textures. The point cloud is triangulated and decimated so it adequately represents the object geometry. Using EWA splatting, we compute textures patches for all triangles in the mesh. In an iterative process, the size of the texture patches is chosen adaptively such that texture information is preserved during the conversion. The texture filtering capabilities of EWA splatting ensure that no texture aliasing occurs. Finally, the texture patches are compiled into a texture atlas. Aside from colors, other surface attributes can be treated similarly. Normal maps can be computed to allow for further simplification of the output mesh while maintaining high visual quality.Item A Unified Lagrangian Approach to Solid-Fluid Animation(The Eurographics Association, 2005) Keiser, Richard; Adams, Bart; Gasser, Dominique; Bazzi, Paolo; Dutré, Philip; Gross, Markus; Marc Alexa and Szymon Rusinkiewicz and Mark Pauly and Matthias ZwickerWe present a framework for physics-based animation of deforming solids and fluids. By merging the equations of solid mechanics with the Navier-Stokes equations using a particle-based Lagrangian approach, we are able to employ a unified method to animate both solids and fluids as well as phase transitions. Central to our framework is a hybrid implicit-explicit surface generation approach which is capable of representing fine surface detail as well as handling topological changes in interactive time for moderately complex objects. The generated surface is represented by oriented point samples which adapt to the new position of the particles by minimizing the potential energy of the surface subject to geometric constraints.We illustrate our algorithm on a variety of examples ranging from stiff elastic and plasto-elastic materials to fluids with variable viscosity.