Walk-Through Illustrations Frame-Coherent Pen-and-Ink Style in a Game Engine

Walk-Through IllustrationsFrame-Coherent Pen-and-Ink Stylein a Game Engine Bert FreudenbergMaic MasuchThomas 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 60ies

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

Games & NPR • Pencil Whipped

Games & NPR • 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 = 18 + 16 + 8 • Draw? No YesMaybe

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

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

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 • Minimum filtering

Ink Maps • Intelligent filtering?

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 Ink Maps

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, MagdeburgOpen now until 2nd 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

Walk-Through Illustrations Frame-Coherent Pen-and-Ink Style in a Game Engine