1. Texture Mapping by Model Pelting and Blending
Deva Ramanan
Hao Zhang

2. Texture mapping Improve surface appearance
Versatile: image map, displacement map, reflection map …
Relative small amount of computation
(from Pixar shutterbug image series)

3. Texture mapping (contd.)
Requires “good” parameterization
Minimize distortion
Appears to be seamless

4. Subdivision surfaces One single mesh for any topology
Multiple NURBS patches
Maintain smoothness (static and animated)
(u,v)-parameterization
Tensor product B-Spline patches
Shapes of arbitrary topology
Cf. “Character animation” (SS98)
(SS98)

5. Texture mapping on subdivision surfaces
3D Solid Textures
Multiple local textures
Blend overlapping regions at the seam
Goals (again):
Minimize distortion
Seam blending

6. Texture coordinates Linear interpolation [Stam98]
texture coords as local (u,v) parameterization
yields C1 interior and C0 cross-boundary
Catmull-Clark on scalar field
position (x,y,z)  position+texture (x,y,z,s,t)
subdivide in 5D
yields C2 interior and C1 on extra-ordinary points
needs texture coordinates on M0
(SS98)

7. Texture mapping analogy: The pelt
Initial control mesh ~ rubber sheet
Stretch mesh to form a pelt
Paint texture on the pelt

8. Pelting: The Cut
Cut: User specified connected tree of edges

9. Pelting: Implementation
Approximate rubber sheet by a spring-mass system
Distortion measure:
Elastic energy
Scale invariance

10. Simulate a spring-mass system
System evolves so as to minimize energy

11. Blending Texture: Approach
Split M0 into 2 overlapping regions:
-Uo: Pelt Region
-U1: Patch Region
Use blend functions b0() & b1() along overlapping regions

12. Example Patch
C0 + C1 + C2 + C3= patch region

13. Review: Domain of ControlP B C D
2D Cubic B Splines:
Catmull/Clark surfaces: P

14. Blend Function
Pelt, Patch, and Overlapping Regions surrounding the Cut C0 C1 C2 C3 C4
b1= cubic B-spline
b0 = 1 - b1

15. Results: Cool Pictures!

16. Evaluation Pelting: Seam blending: Weaknesses:
Novel 3D Spring Mass implementation eliminates “buckling” [Maillot et al 93]
Seam blending:
Painted textures
Weaknesses:
Tiled/tesselated pattern
low polygon count meshes

17. Conclusion Ultimate goal: Minimum distortion
texture coordinate control