Relief: A Modeling by Drawing Tool

1. Relief: A Modeling by Drawing Tool David Bourguignon1Raphaëlle Chaine2 Marie-Paule Cani3George Drettakis4 1Princeton University / INRIA Rocquencourt 2LIRIS / CNRS / UCBL 3GRAVIR / INP Grenoble 4REVES / INRIA Sophia-Antipolis

2. Outline • Motivation • Previous Work • Tool Workflow • Reconstruction • Adaptive Sampling & Depth Inference • Tool Interface • Results

3. On Users • Most people draw • Writing alternative • Few people sculpt • Play-Doh days long gone • Materials difficult to handle

4. Goals • Use 2D tools to perform 3D operations

5. Goals • Use 2D tools to perform 3D operations • Model global and local surface

6. Goals • Use 2D tools to perform 3D operations • Model global and local surface • Input: just plain strokes

7. Goals • Use 2D tools to perform 3D operations • Model global and local surface • Input: just plain strokes • Output: triangle mesh

8. Outline • Motivations • Previous Work • Tool Workflow • Reconstruction • Adaptive Sampling & Depth Inference • Tool Interface • Results

9. Previous Work • Depth painting [Williams, 1990] +

10. Previous Work • Gradient editing [van Overveld, 1996]

11. Previous Work • Maya 6.0 Artisan [Alias, 2004]

12. Outline • Motivations • Previous Work • Tool Workflow • Reconstruction • Adaptive Sampling & Depth Inference • Tool Interface • Results

13. Tool Workflow • First step: drawing input • Displacement map • mid-grey = 0 • white > 0 • black < 0 Brush Pencil Model of 3D sphere

14. Tool Workflow • First step: drawing • Displacement map • 2D shape boundary(in green) • defines drawing mask

15. Tool Workflow • First step: drawing • Displacement map • 2D shape boundary • Displacement regions (from 2 maps)

16. Tool Workflow • Second step: modeling • Displace existing vertices

17. Tool Workflow • Second step: modeling • Displace existing vertices • Create new surface patch

18. Modeling by drawing Changing viewpoint Tool Workflow • Changing viewpoint

19. Reconstruction • Based on evolving pseudo-manifold [Chaine, 2003]

20. Reconstruction • Based on evolving pseudo-manifold [Chaine, 2003] • Satisfy our requirements • Arbitrary number of connected components

21. Reconstruction • Based on evolving pseudo-manifold [Chaine, 2003] • Satisfy our requirements • Arbitrary number of connected components • Handle points off shape boundary

22. Reconstruction • Based on evolving pseudo-manifold [Chaine, 2003] • Satisfy our requirements • Arbitrary number of connected components • Handle points off shape boundary • Interactive (5k points per second)

23. 2D reconstruction • Start: pseudo-curve lies on oriented edges of Delaunay triangulation

24. 2D reconstruction • During: pseudo-curve evolves as long as oriented Gabriel criterion is not met

25. 2D reconstruction • Stop: topologically consistent set of oriented edges

26. Sampling and Depth • Adaptive sampling • Displacement map • Pencil and brush data in color buffer Color buffer

27. Sampling and Depth • Adaptive sampling • Displacement map • Approximate disp. mapsampled at existing vertices

28. Sampling and Depth • Adaptive sampling • Displacement map (D) • Vertex-Sampled disp. map (V) • Error map E = 1 – ABS(D – V) • Arbitrary error value

29. Sampling and Depth • Adaptive sampling • Displacement map • Approximate disp. map • Error map • Sampling [Alliez, 2002]

30. Sampling and Depth • Adaptive sampling • Depth inference • Identify surface vertices Vertices ID buffer

31. Sampling and Depth • Adaptive sampling • Depth inference • Identify surface vertices • Assign depth values Depth buffer

32. Sampling and Depth • Adaptive sampling • Depth inference • Identify surface vertices • Assign depth values • Infer depth values • from existing surface • by depth propagation

33. Outline • Motivations • Previous Work • Tool Workflow • Reconstruction • Adaptive Sampling & Depth Inference • Tool Interface • Results

34. Tool Interface • Hole marks • Comic books production Hole marks Stone #3 (Avalon Studios)

35. Tool Interface • Hole marks • Comic books production • Our system Hole mark

36. Tool Interface • Video: Basic interface

37. Tool Interface • Blobbing Drawing Distance field Height field White shading Surface

38. Tool Interface • Depth modes (chosen by menu) Depth inference Modeling “at depth” Frisket mode

39. Video • Modeling a tree Paper sketch 3D model obtained with Relief

40. Outline • Motivations • Previous Work • Tool Workflow • Reconstruction • Adaptive Sampling & Depth Inference • Tool Interface • Results

41. Results • Models (1k to 4k points)

42. Discussion • Intuitive shading convention

43. Discussion • Intuitive shading convention • Problems with drawing metaphor • No continuous visual feedback • Provide two modes

44. Discussion • Intuitive shading convention • Problems with drawing metaphor • No continuous visual feedback • Difficult to obtain continuous shading • Provide higher-level drawing tools

45. Conclusion • Modeling by drawing, but imprecise

46. Conclusion • Modeling by drawing, but imprecise • Future work • Speedup with local 3D reconstruction

47. Conclusion • Modeling by drawing, but imprecise • Future work • Speedup with local 3D reconstruction • Improve depth inference

48. Conclusion • Modeling by drawing, but imprecise • Future work • Speedup with local 3D reconstruction • Improve depth inference • Image-space and object-space sampling

49. Acknowledgements This work has been performed while the first author was a visiting research fellow at Princeton University, supported by an INRIA post-doctoral fellowship. Many people have indirectly contributed to it. We would like to thank: Adam Finkelstein, Szymon Rusinkiewicz, Jason Lawrence, Pierre Alliez, Mariette Yvinec, Laurence Boissieux, Laure Heïgéas, Laks Raghupathi, Olivier Cuisenaire, Bingfeng Zhou.