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sculpting meshes with self-adaptive topology

sculpting meshes with self-adaptive topology. Freestyle. Lucian Stanculescu a,b , Raphaëlle Chaine a , Marie- Paule Cani b,c a LIRIS, University of Lyon, France b LJK, University of Grenoble, France c INRIA, France. Introduction Quasi-uniform mesh Time evolution Sculpting tools

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sculpting meshes with self-adaptive topology

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  1. sculpting meshes with self-adaptive topology Freestyle Lucian Stanculescua,b , RaphaëlleChainea , Marie-PauleCanib,c a LIRIS, University of Lyon, France bLJK, Universityof Grenoble, France c INRIA, France Freestyle

  2. Introduction • Quasi-uniform mesh • Time evolution • Sculpting tools • Results • Conclusion and future work • Demo Contents Freestyle

  3. Goal : Develop an intuitive sculpting system • professional artists and amateur users • Digital sculpting : important tool for 3D content creation • animated movies, special effects, computer games • Models behind professional applications : • polygonal (no changes in topological genus) • ZBrush, Mudbox, Sculptris, Blender • regular grids (surface extraction, no color) • 3D Coat • Specific workflow • limitations 1. Introduction Freestyle

  4. Grid-based methods (Galyean and Hughes ‘91) • Deformation tools (Ferley et al. ‘01), virtual clay (Dewaele et al. ‘04) • Surface extraction • Implicit methods : Blob Tree • Deformations by Warp Curves (Sugihara et al. ‘10) • Hierarchy of tools • Particlesystems (Pons and Boissonnat ‘07, Debard et al. ‘07) • topology changes, quality adaptive mesh – relaxation process slow • Mesh-based • Model-based deformations : Laplacian editing (Sorkine et al. ‘04) • Space deformations (Angelidis et al. ‘04, von Funck et al. ‘06) • No change in topology 1. Introduction :: related work Freestyle

  5. Enable topological changes in mesh models • Interactive • Why meshes ? • No relaxationand complex reconstruction • Large variety of tools • Fast rendering on GPU 1. Introduction :: objective Freestyle

  6. Main idea : manifold mesh with uniform sampling • Advantages : • Simplify collision detection • Easily handle changes in topology • Simple tracking of surface deformations 2. Quasi-uniform mesh Freestyle

  7. D1. Δ tight mesh – closed manifold mesh M with edges < Δ • Constructed by splitting edges > Δ • Advantage: vertices reflect geometry (precision Δ: detail) • edge split 2. Quasi-uniform mesh :: detail Freestyle

  8. D2. Compliance with d • iterate over all edges • collapse if edge < d • ! Favored for most edges but not guaranteed • edge collapse 2. Quasi-uniform mesh :: mesh quality Freestyle

  9. D3. Quasi-uniform mesh • d < Δ,closed manifold mesh M • compliance with d • restoration of Δ tightness. • d < Δ / 2 • d: better uniformity, increase in vertex creation-deletion events 2. Quasi-uniform mesh Freestyle

  10. Vertices displaced by deformation fields • Apply compliance with d • Restore Δtightness • Handle topology • Difficulty • Detect important events before : • Loss in detail • Self-intersection 3. Time evolution Freestyle

  11. D4. Θ : minimum thickness supported by quasi-uniform mesh Θ : minimum distance between two non-adjacent vertices. Simple collisions : vertex-vertex connecting 1-rings 3. Time evolution Freestyle

  12. D5. μ : maximum allowed displacement for a vertex. 4 μ ² ≤ Θ² - Δ² / 3 3. Time evolution Freestyle

  13. Difficulty : maintain manifold mesh • Neighbourhood cleanup • Handle degenerate cases • Delete coinciding triangles (a) • Split surface at coinciding vertices and edges (a, b) • a) b) 3. Time evolution Freestyle

  14. Displacement fields • Space deformations • volume preserving • Model dependent • normals, geodesic distance… • Deformation applied discretely • Large displacements • divided • max(norm) < μ 4. Sculpting tools Freestyle

  15. 4. Sculpting tools :: space Sweep deform (volume preserving) Freestyle

  16. 4. Sculpting tools :: model Inflate (normals) Freestyle

  17. 5. Results • Object : 30k points • Collision detection – most time expensive • GPU implementation (x 30 speed-up, Le Grand, GPU Gems 3) • Interactive ~200k points • no optimization (VBO regions, GPU collision) Freestyle

  18. 6. Conclusions • Handle arbitrary changes in topology • simple quasi-uniform framework • Intuitive model based on two physical properties of materials • surface detail and bulk thickness • Closer to real-life sculpting • auto-refinement • changes in topology Freestyle

  19. 6. Future work • Sharp features • Sculpting curves • Fast approximate Boolean operations • Surface painting • Adaptive sampling (local quasi-uniform meshes) • Further validation by professional and amateur users Freestyle

  20. 7. Demo Freestyle

  21. Thank you ! Freestyle

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