WalkThrough Illustrations FrameCoherent PenandInk Style in a Game Engine

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Walk-Through IllustrationsFrame-Coherent
Pen-and-Ink Stylein a Game Engine

• Bert FreudenbergMaic Masuch Thomas
  Strothotte
• Institut für Simulation und Graphik
• Universität Magdeburg

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Walk-Through Illustrations

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

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Project background

• Excavation in 60ies

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Project background

• Virtual reconstruction since 1997

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Project background

• Visualizing uncertainty ? NPR

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Project background

• New challenge Museum exhibition

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Project background

• Three projectors in spherical room

5.8 m
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Project background

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

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Project background

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

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Games NPR

• Pencil Whipped

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Games NPR

• NPRQuake

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Games NPR

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

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Pen-and-Ink

• Elements
• Outlines
• Silhouettes
• Discontinuities
• Surfaces
• Hatching
• Detail

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Outlines

• New idea
• 42 18 16 8
• Draw? No Yes Maybe

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Outlines

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

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Outlines

• Determining convexity
• convex(e) ? v N lt 0

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Outlines

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

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Surfaces

• Textures
• Nothing else is fast enough

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Surfaces

• Plain texture on a single quad

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Surfaces

• Conventional mipmapping (average filtering)

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Surfaces

• Average-filtering an ink texture
• All gray!

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Surfaces

• Solution
• Hatch Maps
• Abuse mipmapping

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Hatch Maps

• Mipmap levels for hatch maps
• Mostly b/w!

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Hatch Maps

• Mipmapping with hatch maps

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Hatch Maps

• Mipmapping with hatch maps, trilinear

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Surfaces

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

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Ink Maps

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

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Ink Maps

• Average filtering

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Ink Maps

• Average filtering

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Ink Maps

• Minimum filtering

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Ink Maps

• Minimum filtering

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Ink Maps

• Intelligent filtering?

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Ink Maps

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

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Ink Maps

• Intelligent filtering?
• Let an artist do it!

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Ink Maps

• Hand drawn

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Walk-Through Illustrations

• What else?
• Color Shading

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Walk-Through Illustrations

• What else?
• Hybrid scenes

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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

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Walk-Through Illustrations

• Prototype implementation (2000)
• Actual exhibition looks different

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Walk-Through Illustrations

• Exhibition
• Museum of Cultural History, MagdeburgOpen now
  until 2nd December 2001

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Walk-Through Illustrations

• Future directions
• Add shading
• Use colored lines
• LOD

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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