1. Non-Photorealistic Rendering Greg Turk College of Computing and GVU Center

2. Painterly Rendering for Animation Barbara Meier, SIGGRAPH 1996

3. Painterly Rendering Issues Frame-to-frame coherence (maintain strokes across time) Idea: fix brush strokes in screen-space Problem: shower door effect Better idea: fix brush strokes to object

4. Painting Pipeline Brushes (color & opacity):

5. Different Brushes and Orientation Fields

6. Draw Image in Layers

7. Video

8. Pen and Ink Sketches Mike Salisbury, Michael Wong, John Hughes and David Salesin, SIGGRAPH 1997

9. Pen and Ink Given: grayscale image (e.g. photo) Make: pen-and-ink illustration Approach: Gray scale image Direction field Brush Strokes Final Image + + =

10. Pen and Ink Sketches Tone Map Orientation Field Strokes

11. Pen and Ink Sketches Tone Map Orientation Field Strokes

12. Stroke Details Strokes are B-spline curves (similar to Bezier) Strokes clipped to silhouettes Stroke density controlled by blurred stroke image Strokes follow orientation field

13. Painting Orientation Field

14. Stroke Density Strokes Blurred Strokes

16. Stroke Density Varies with Drawing Size

18. Art-Based Rendering Of Fur, Grass and Trees Kowalski, Markosian, Northrup, Bourdev, Barzel and Hughes, SIGGRAPH 2000

19. Approach Real-time rendering Use reference images for color and object ID Place “strokes” based on density Try to place same strokes on next frame

20. Reference Images: Hardware Rendering

21. Final Image

22. Stroke Drawing

25. “Illustrating Smooth Surfaces” Aaron Hertzman and Denis Zorin SIGGRAPH 2000

26. Goals Create pen-and-ink strokes based on 3D geometry Show silhouettes Have cross-hatching

27. Issues Silhouette detection Orientation field (use curvature) Hatching Undercuts

28. Silhouette Detection

29. Orientation Field Smoothing

30. Orientation Field and Shading

31. Hatching

32. Hatching and Undercuts

33. Results

35. Other NPR Cel Animation Painterly Video Cel Video ???

36. Painterly Video “What Dreams May Come”

37. Cel Animation: Zelda Windwalker

38. Cel-Like Video

39. End