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Point-based techniques

CAGD&CG. Point-based techniques . Mei ’ e Fang Wednesday, November 1, 2006. contents. relative c onceptions of point-based surfaces point-based representations point-based geometry processing point-based rendering a paper on computing areas of point-based surfaces. main references.

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Point-based techniques

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  1. CAGD&CG Point-based techniques Mei’e Fang Wednesday, November 1, 2006

  2. contents • relative conceptions of point-based surfaces • point-based representations • point-based geometry processing • point-based rendering • a paper on computing areas of point-based surfaces

  3. main references • Leif Kobbelt, Mario Botsch. A survey of point-based techniques in computer graphics. Computers & Graphics, 2004 28: 801-814. • Yu-Shen Liu, Jun-Hai Yong, Hui Zhang, Dong-Ming Yan, Jia-Guang Sun. A quasi-Monte Carlo method for computing areas of point-sampled surfaces. CAD, 2006 38: 55-68.

  4. Relative conceptions

  5. NURBS → Meshes → Point-clouds The topological consistency becomes more and more simply.

  6. neighborhoods and normals two kinds of neighborhoods • Euclidean neighborhoods not suited for irregularly sampled surfaces and unreliable in some cases • k-nearest neighborhoods a naturally adaptive neighborhood relation

  7. Amenta, N., Bern, M., Kamvysselis, M., 1998. A new Voronoi-based surface reconstruction algorithm. In: Proc. of ACM SIGGRAPH 98. • Andersson, M., Giesen, J., Pauly, M., Speckmann, B., 2004. Bounds on the k-neighborhood for locally uniformly sampled surfaces. In: Proc. of Symp. on Point-Based Graphics 04. pp. 167–171. • J. Sankaranarayanan, H. Samet, and A. Varshney, A Fast k-Neighborhood Algorithm for Large Point Clouds. Proceedings of the Symposium on Point-Based Graphics July 29 - 30, 2006, Boston, MA

  8. the estimation of normals the covariance matrix: The eigenvector corresponding to thesmallest eigenvalue gives an estimate for the normal direction. Hoppe, H., DeRose, T., Duchamp, T., McDonald, J., Stuetzle, W., 1992. Surface reconstruction from unorganized points. In: Proc. of ACM SIGGRAPH92. pp. 71–78.

  9. Point-based representations purely point-based representations surface splats moving least-squares surfaces

  10. purely point-based representations point clouds

  11. Grossman, J. P., Dally, W. J., 1998. Point sample rendering. In: Proc. Of Eurographics Workshop on Rendering 98. pp. 181–192. Similar to image-based approaches, this representation is also constructed from several views of an input object, but it differs in that each pixel is a surface sample containing geometric position and (view-independent) surface color.

  12. Kalaiah, A., Varshney, A., 2003. Statistical point geometry. In: Proc. of Eurographics Symposium on Geometry Processing 03. pp. 107–115. using a hierarchical PCA analysis to partition the geometry and its attributes (normals and colors) into a set of local Gaussian probability distributions

  13. Botsch, M., Wiratanaya, A., Kobbelt, L., 2002. Efficient high quality rendering of point sampled geometry. In: Proc. of Eurographics Workshop on Rendering 02. considering the quantization precision to minimize redundancy and using a hierarchical PBR to reduce the memory cost

  14. PBR of a circle with different quantization levels (left: 5 bit, right 10 bit) and different sampling densities (top:2p/32, bottom: 2p/1024).

  15. surface splats Zwicker, M., Pfister, H., van Baar, J., Gross, M., 2001. Surface splatting. In:Proc. of ACM SIGGRAPH 01. pp. 371–378. circular disks→elliptical splats

  16. elliptical splats two tangential axes: the principal curvature directions of the underlying surface two respective radii: inversely proportional to the corresponding minimum and maximum curvatures superiorities: the same topological flexibility as pure point clouds; the same approximation order as triangle meshes; locally the best linear approximant to a smooth surface;

  17. representing sharp features Pauly, M., Keiser, R., Kobbelt, L., Gross, M., 2003. Shape modeling with point-sampled geometry. In: Proc. of ACG SIGGRAPH 03.

  18. moving least-squares surfaces His found by minimizing gis found by minimizing The weight function

  19. • Alexa, M., Behr, J., Cohen-Or, D., Fleishman, S., Levin, D., Silva, C. T., 2003. Computing and rendering point set surfaces. IEEE Transactions on Visualization and Computer Graphics 9 (1), 3–15. • Alexa, M., Adamson, A., 2004. On normals and projection operators for surfaces defined by point sets.In: Proc. of Symp. on Point- Graphics 04.pp. 149–155.

  20. Amenta, N., Kil, Y., 2004. Defining point-set surfaces. In: Proc. of ACM SIGGRAPH 04.

  21. Point-based geometry processing

  22. noise removal Pauly, M., Gross, M., 2001. Spectral processing of point-sampled geometry. In: Proc. of ACM SIGGRAPH 01.

  23. Original Patch Gaussian Wiener noise+blur Layout Filter Filter

  24. summary • versatile spectral decomposition of point-based models • effective filtering • adaptive resampling • efficient processing of large point-sampled models

  25. Pauly, M., Keiser, R., Gross, M., 2003. Multi-scale feature extraction onpoint-sampled surfaces. In: Proc. of Eurographics 03.

  26. Weyrich, T., Pauly, M., Heinzle, S., Keiser, R., Scandella, S., Gross, M., 2004.Post-processing of scanned 3D surface data. In: Proc. of Symp. on Point-Based Graphics 04. pp. 85–94.

  27. decimation three kinds of decimation methods Pauly, M., Gross, M., Kobbelt, L., 2002. Efficient simplification of point-sampled surfaces. In: Proc. of IEEE Visualization 02. • hierarchical clustering method • iterative simplification • particle simulation

  28. clustering method

  29. iterative simplification

  30. particle simulation

  31. comparison

  32. Wu, J., Kobbelt, L., 2004. Optimized subsampling of point sets for surfacesplatting. In: Proc. of Eurographics 04. a simplification method especially designed for splat-based surface

  33. editing Zwicker, M., Pauly, M., Knoll, O., Gross, M., 2002. PointShop 3D: An interactive system for point-based surface editing. In: Proc. of ACM SIGGRAPH02.

  34. Adams, B., Wicke, M., Dutr´e, P., Gross, M., Pauly, M., Teschner, M., 2004. Interactive 3D painting on point-sampled objects. In: Proc. of Symp. on Point-Based Graphics 04. pp. 57–66.

  35. deformation Pauly, M., Keiser, R., Kobbelt, L., Gross, M., 2003. Shape modeling with point-sampled geometry. In: Proc. of ACG SIGGRAPH 03.

  36. PDE-based segmentation, texture synthesis, texture inpainting and geometry smoothing

  37. Constructive Solid Geometry technique • references • Clarenz, U., Rumpf, M., Telea, A., 2004. Finite elements on point based surfaces.In: Proc. of Symp. on Point-Based Graphics 04. pp. 201–211. • Adams, B., Dutre, P., 2003. Interactive boolean operations on surfel-bounded solids. In: Proc. of ACM SIGGRAPH 03. pp. 651–656. • Adams, B., Dutre, P., 2004. Boolean operations on surfel-bounded solids using programmable graphics hardware. In: Proc. of Symp. on Point-Based Graphics 04. pp. 19–24.

  38. Point-based rendering

  39. Botsch, M., Spernat, M., Kobbelt, L., 2004.Phong splatting. In: Proc. of Symp. on Point-Based Graphics 04.

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