1. Surface Aging by Impacts E. Paquette 1,2, P. Poulin 1, G. Drettakis 2 1 Université de Montréal 2 iMAGIS/GRAVIR-REVES-INRIA

2. GI 2001 Université de Montréal iMAGIS Context Realistic rendering Synthetic objects look too perfect Aging effects

3. GI 2001 Université de Montréal iMAGIS Previous Work Specific effects –Dirt & dust [Miller94, Hsu95] –Sculpting & tracks [Wang95, Sumner98] –Weathering [Dorsey96b, Dorsey99] –Corrosion [Dorsey96a, Merillou01] –Cracks & fracture [Hirota98, O’Brien99] –Scratches [Merillou01]

4. GI 2001 Université de Montréal iMAGIS Previous Work Specific effects –Dirt & dust [Miller94, Hsu95] –Sculpting & tracks [Wang95, Sumner98] –Weathering [Dorsey96b, Dorsey99] –Corrosion [Dorsey96a, Merillou01] –Cracks & fracture [Hirota98, O’Brien99] –Scratches [Merillou01]

5. GI 2001 Université de Montréal iMAGIS Previous Work Specific effects –Dirt & dust [Miller94, Hsu95] –Sculpting & tracks [Wang95, Sumner98] –Weathering [Dorsey96b, Dorsey99] –Corrosion [Dorsey96a, Merillou01] –Cracks & fracture [Hirota98, O’Brien99] –Scratches [Merillou01]

6. GI 2001 Université de Montréal iMAGIS Previous Work Imperfection systems [Becket90, Wong97]

7. GI 2001 Université de Montréal iMAGIS Impacts Impacts on surface –Scratches –Abrasion –Compaction

8. GI 2001 Université de Montréal iMAGIS Compaction Surface compressed Many impacts Empirical simulation

9. GI 2001 Université de Montréal iMAGIS Real Examples

10. GI 2001 Université de Montréal iMAGIS Motivation Empirical simulation –Simplicity –Efficiency –User interaction

11. GI 2001 Université de Montréal iMAGIS Outline Overview Inputs Simulation Results Conclusion

12. GI 2001 Université de Montréal iMAGIS Overview user parameters tools original object aged object intersectdeform refine

13. GI 2001 Université de Montréal iMAGIS Original Object Mesh –Common representation –Triangle mesh

14. GI 2001 Université de Montréal iMAGIS User Interface Tools –size Object deformation –compaction volume Impacts –location –direction

15. GI 2001 Université de Montréal iMAGIS Simulation Intersection Refinement Deformation user parameters tools original object aged object intersectdeform refine

16. GI 2001 Université de Montréal iMAGIS Intersection tool path object intersected faces

17. GI 2001 Université de Montréal iMAGIS Tool Footprint Footprint of tool on object Sharp edges (curvature) Perpendicular edges (to the path) Tools

18. GI 2001 Université de Montréal iMAGIS Tool Footprint Footprint of tool on object Sharp edges (curvature) Perpendicular edges (to the path) Less refinement More refinement Tools

19. GI 2001 Université de Montréal iMAGIS Tool Footprint Footprint of tool on object Sharp edges (curvature) Perpendicular edges (to the path) Less refinement More refinement tool path Tools

20. GI 2001 Université de Montréal iMAGIS Feature Points Distribute feature points Tool edges –curvature (difference of normals) –perpendicular to path –length wrt user feature size –jittering

21. GI 2001 Université de Montréal iMAGIS Feature Points Points representing required refinement tool path path parallel path perpendicular border (curvature)

22. GI 2001 Université de Montréal iMAGIS Mesh Refinement Project feature points Refine if nb > threshold tool impact

23. GI 2001 Université de Montréal iMAGIS Mesh Refinement Quaternary subdivision Restriction and anchoring –avoid T-vertices subdivide restrict anchor

24. GI 2001 Université de Montréal iMAGIS Problem: Folding Try to avoid surface folding tool object folded surface

25. GI 2001 Université de Montréal iMAGIS Problem: Self-intersection Try to avoid self-intersection object self- intersects

26. GI 2001 Université de Montréal iMAGIS Deformation Direction Constrain surface movement Reduce self-intersections and folding deformation directions

27. GI 2001 Université de Montréal iMAGIS Deformation Steps object vertex

28. GI 2001 Université de Montréal iMAGIS Deformation Steps

29. GI 2001 Université de Montréal iMAGIS Deformation Steps

30. GI 2001 Université de Montréal iMAGIS Deformation Steps projected feature points tool

31. GI 2001 Université de Montréal iMAGIS Deformation Steps

32. GI 2001 Université de Montréal iMAGIS Deformation Steps

33. GI 2001 Université de Montréal iMAGIS Deformation Steps

34. GI 2001 Université de Montréal iMAGIS Deformation Steps project along deformation direction on copy

35. GI 2001 Université de Montréal iMAGIS Deformation Steps deformed surface

36. GI 2001 Université de Montréal iMAGIS Output Aged object Recompute normals N?

37. GI 2001 Université de Montréal iMAGIS Normals Weighted average N =  w i N i weight ~ face subtended angle N N0N0 N5N5 N1N1 N4N4 N2N2 N3N3

38. GI 2001 Université de Montréal iMAGIS Output 3D viewer Save –Render with any standard renderer (we use Maya)

39. GI 2001 Université de Montréal iMAGIS Video

40. GI 2001 Université de Montréal iMAGIS Target Real Images Real photographs as goals trunk

41. GI 2001 Université de Montréal iMAGIS Target Real Images stairsdoor

42. GI 2001 Université de Montréal iMAGIS Target Real Images metal plate door & frame

43. GI 2001 Université de Montréal iMAGIS User Interaction Trial and error –tools –tool size –compaction volume –impact location and direction 30 minutes to 2 hours user time per object

44. GI 2001 Université de Montréal iMAGIS Synthetic Aged Trunk realagedclean

45. GI 2001 Université de Montréal iMAGIS Synthetic Aged Door realagedclean

46. GI 2001 Université de Montréal iMAGIS Synthetic Aged Door realaged

47. GI 2001 Université de Montréal iMAGIS Synthetic Aged Door Frame realagedclean

48. GI 2001 Université de Montréal iMAGIS Synthetic Aged Stairs realagedclean

49. GI 2001 Université de Montréal iMAGIS Synthetic Aged Stairs realaged

50. GI 2001 Université de Montréal iMAGIS Synthetic Aged Metal Plate realagedclean

51. GI 2001 Université de Montréal iMAGIS Simulation Statistics StairsTrunkFramePlateDoor Impacts128149300234276 Total (seconds) 4.13s4.78s7.59s6.17s8.54s Average (milliseconds) 32ms 25ms26ms31ms Athlon 600 MHz Linux PC

52. GI 2001 Université de Montréal iMAGIS Simulation Statistics Mesh size StairsTrunkFramePlateDoor original6 k2 k35221 k final22 k18 k23 k20 k25 k regular232000 k80000 k11000 k16000 k32000 k

53. GI 2001 Université de Montréal iMAGIS Rendering Time SGI Onyx 4 x R4400, 200 MHz

54. GI 2001 Université de Montréal iMAGIS Conclusion Increased realism Adaptive refinement Reduced –folding –self-intersection Simple & Efficient Intuitive & easy to use

55. GI 2001 Université de Montréal iMAGIS Future Work Surface –refinement, representation Impacts specification –from possible results –extraction from images Other effects –pealing, abrasion, scratches, dirt

56. GI 2001 Université de Montréal iMAGIS Acknowledgments Grants & scholarships –FCAR, NSERC, MRI-MEQ Rendering software –Alias|Wavefront iMAGIS is a joint project of CNRS/INRIA/UJF/INPG