1. Walk-Through Illustrations Frame-Coherent Pen-and-Ink Style in a Game Engine Bert Freudenberg Maic Masuch Thomas Strothotte Institut für Simulation und Graphik Universität Magdeburg

2. Walk-Through Illustrations Overview Project background Games & NPR Our pen-and-ink style Outlining Surfaces Future directions

3. Project background Excavation in 60ies

4. Project background Virtual reconstruction since 1997

5. Project background Visualizing uncertainty  NPR

6. Project background New challenge: Museum exhibition

7. Project background Three projectors in spherical room 5.8 m

8. Project background Real-time visualization? Usual answer: Multi-pipe Onyx + Performer Big $$$ Boring Our answer: 3 PCs + Game Engine Much cheaper More fun

9. Project background 3D Game Engine provides Efficient 3D content rendering Networking for different views Interaction Just need real-time NPR in that engine!

10. Games & NPR Pencil Whipped

11. Games & NPR NPRQuake

12. Games & NPR Why no commercial real-time NPR games? Must support wide range of hardware Processor speed Graphics board Rather new field Probably soon

13. Pen-and-Ink Elements Outlines Silhouettes Discontinuities Surfaces Hatching Detail

14. New idea: 42 =18+16+8 Draw?NoYesMaybe Outlines

15. Modeling edges sharp or smooth Preprocess determine convexity Draw edge if sharp, or smooth & convex & silhouette Outlines

16. Determining convexity convex(e)  v · N < 0 Outlines N v e

17. Drawing edges GL_LINES Display list for sharp edges Silhouettes immediate Outlines

18. Surfaces Textures Nothing else is fast enough

19. Surfaces Plain texture on a single quad

20. Surfaces Conventional mipmapping (average filtering)

21. Surfaces Average-filtering an ink texture All gray!

22. Surfaces Solution Hatch Maps Abuse mipmapping

23. Hatch Maps Mipmap levels for hatch maps Mostly b/w!

24. Hatch Maps Mipmapping with hatch maps

25. Hatch Maps Mipmapping with hatch maps, trilinear

26. Surfaces Uniform Hatching Hatch Maps Detail / Structure Ink Maps

27. Idea Use hand-drawn maps Problem How to generate mipmap levels

28. Ink Maps Average filtering

29. Ink Maps Average filtering

30. Ink Maps Minimum filtering

31. Ink Maps Minimum filtering

32. Ink Maps Intelligent filtering?

33. Ink Maps Intelligent filtering? Vectorize Draw each level for constant width Select lines to maintain tone and texture in a pleasing way How?

34. Ink Maps Intelligent filtering? Let an artist do it!

35. Ink Maps Hand drawn

36. Walk-Through Illustrations What else? Color + Shading

37. Walk-Through Illustrations What else? Hybrid scenes

38. Walk-Through Illustrations Results Extended a game engine for NPR Faster silhouettes Mipmap-based pen-and-ink textures Frame-coherent Constant line width Constant density

39. Walk-Through Illustrations Prototype implementation (2000) Actual exhibition looks different

40. Walk-Through Illustrations Exhibition Museum of Cultural History, Magdeburg Open now until 2 nd December 2001

41. Walk-Through Illustrations Future directions Add shading Use colored lines LOD

42. Walk-Through Illustrations Acknowledgements Co-Authors Maic Masuch, Thomas Strothotte Programming, Modelling Niklas Röber, Thomas Fuchs Museum of Cultural History, Magdeburg Sebastian Kreiker, Babette Ludowici