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Published byMagnus Harper Modified over 9 years ago
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Non-Photorealistic Rendering Greg Turk College of Computing and GVU Center
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Painterly Rendering for Animation Barbara Meier, SIGGRAPH 1996
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Painterly Rendering Issues Frame-to-frame coherence (maintain strokes across time) Idea: fix brush strokes in screen-space Problem: shower door effect Better idea: fix brush strokes to object
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Painting Pipeline Brushes (color & opacity):
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Different Brushes and Orientation Fields
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Draw Image in Layers
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Video
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Pen and Ink Sketches Mike Salisbury, Michael Wong, John Hughes and David Salesin, SIGGRAPH 1997
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Pen and Ink Given: grayscale image (e.g. photo) Make: pen-and-ink illustration Approach: Gray scale image Direction field Brush Strokes Final Image + + =
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Pen and Ink Sketches Tone Map Orientation Field Strokes
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Pen and Ink Sketches Tone Map Orientation Field Strokes
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Stroke Details Strokes are B-spline curves (similar to Bezier) Strokes clipped to silhouettes Stroke density controlled by blurred stroke image Strokes follow orientation field
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Painting Orientation Field
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Stroke Density Strokes Blurred Strokes
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Stroke Density Varies with Drawing Size
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Art-Based Rendering Of Fur, Grass and Trees Kowalski, Markosian, Northrup, Bourdev, Barzel and Hughes, SIGGRAPH 2000
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Approach Real-time rendering Use reference images for color and object ID Place “strokes” based on density Try to place same strokes on next frame
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Reference Images: Hardware Rendering
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Final Image
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Stroke Drawing
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“Illustrating Smooth Surfaces” Aaron Hertzman and Denis Zorin SIGGRAPH 2000
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Goals Create pen-and-ink strokes based on 3D geometry Show silhouettes Have cross-hatching
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Issues Silhouette detection Orientation field (use curvature) Hatching Undercuts
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Silhouette Detection
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Orientation Field Smoothing
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Orientation Field and Shading
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Hatching
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Hatching and Undercuts
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Results
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Other NPR Cel Animation Painterly Video Cel Video ???
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Painterly Video “What Dreams May Come”
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Cel Animation: Zelda Windwalker
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Cel-Like Video
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End
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