NPR
(Non-photorealistic
Rendering)
Billy Davidson
CS 395 Advanced Graphics
January 22, 2004
Non-photorealistic Rendering
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Most computer graphics work strives for
photorealism
Other types of depiction can be more
expressive or artistic
Depict intrinsic or extrinsic properties?
Terminology
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Image
Picture
Intrinsic/Invariant
Extrinsic
Constancy
Constancy
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We do not experience some extrinsic
properties of the image we see
3D -> 2D Mappings
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Sketches by 7-year old children
Depiction
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Depiction is the mapping of properties of
the scene to properties of the picture
Traditional 3D -> 2D geometric projection
is only one possible meaningful mapping
Projections
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Different projections preserve different
intrinsic properties
Vision as Inverse Problem
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V() = “Visual reaction” function
Not invertible due to ambiguity, emotional
factors, etc.
Primary vs. Secondary Space
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Respect local rules but not global ones
Primary vs. Secondary Space
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Tone mapping
Representation Systems
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Spatial system
Primitive system
Attribute system
Mark system
Painterly Rendering
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Tarzan
Pen Strokes
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Bones
Cel Shading
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The Legend of Zelda: The Wind Waker