WalkThrough Illustrations FrameCoherent PenandInk Style in a Game

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

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

Project background Excavation in 60 ies

Project background Virtual reconstruction since 1997

Project background Visualizing uncertainty NPR

Project background New challenge: Museum exhibition

Project background Three projectors in spherical room 5. 8 m

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

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

Games & NPR Pencil Whipped

Games & NPRQuake

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

Pen-and-Ink Elements • Outlines • Silhouettes • Discontinuities • Surfaces • Hatching • Detail

Outlines New idea: 42 = Draw? 18 No + 16 Yes + 8 Maybe

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

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

Outlines Drawing edges • GL_LINES • Display list for sharp edges • Silhouettes immediate

Surfaces Textures • Nothing else is fast enough

Surfaces Plain texture on a single quad

Surfaces Conventional mipmapping (average filtering)

Surfaces Average-filtering an ink texture All gray!

Surfaces Solution • Hatch Maps • Abuse mipmapping

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

Hatch Maps Mipmapping with hatch maps

Hatch Maps Mipmapping with hatch maps, trilinear

Surfaces Uniform Hatching • Hatch Maps Detail / Structure • Ink Maps

Ink Maps Idea • Use hand-drawn maps Problem • How to generate mipmap levels

Ink Maps Average filtering

Ink Maps Average filtering

Ink Maps Minimum filtering

Ink Maps Minimum filtering

Ink Maps Intelligent filtering?

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

Ink Maps Intelligent filtering? • Let an artist do it!

Ink Maps Hand drawn

Walk-Through Illustrations What else? • Color + Shading

Walk-Through Illustrations What else? • Hybrid scenes

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

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

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

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

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