A Very Brief Overview of Non-Photorealistic Rendering

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A Very Brief Overview of Non-Photorealistic
Rendering

• Conrad Albrecht-Buehler
• Graduate Thesis Seminar
• September 24, 2001

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What is Non-Photorealistic Rendering (NPR)?

• Rendering of an image to mimic media other than a
  photograph
• Gooch provide info not readily apparent in a
  photo

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NPRs Usefulness

• New Artistic Tools
• Can provide more useful information than a photo
  might
• Lends attractiveness to visualizations
• New modes of visualization

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NPR Applications

• Artist Tool
• Architecture
• Cinema
• Games
• Scientific Visualization
• Cartography

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Types of NPR

• Image Space Effects
• Perspective Space Effects
• Data Mapped Visualization

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Image Space Effects

• Techniques applied to an output image
• Style filters mimic a familiar artistic style
  by modifying the pixel image
• Some work has been done in automatic media
  generation based on an imput image, e.g.
  watercolor

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From Teece
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From Teece
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From Curtis et al.
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Perspective Space Effects

• Techniques applied on input models
• Much work has been done recreating artistic
  styles using 3D models as subjects
• Toon Shaders typically highlight silhouettes
  based on the model
• Technical and Architectural sketch renderings are
  created from models as well

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From Teece
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From Teece
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From Teece
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From Buchanan and Sousa
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(No Transcript)
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(No Transcript)
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From Teece
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(No Transcript)
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Data Mapped

• Techniques applied to input data and mapped to
  variables
• Cartography
• Scientific Visualization

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From Agrawala and Stolte
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From Healey
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Implementing NPR techniques

• Pencil and Paper
• NPR for gaming
• Toon rendering in real-time
• NPR Quake

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Pencil and Paper Rendering

• Simulating the interaction of paper, pencil lead,
  eraser, and blender based on an observational
  model

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From Buchanan and Sousa
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From Buchanan and Sousa
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From Buchanan and Sousa
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From Buchanan and Sousa
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Cartoon Rendering

• Most cartoon rendering involves heavy, dark
  outlines and flat shading.
• Some work has been done in stylized cartoon
  rendering such as Dr. Suess

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From Kawalski
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From Segas Fur Fighters
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Creating that Toon Look

• The silhouette is the edge between a front and
  back facing polygon
• For every front facing polygon XOR in 1 into the
  F field
• For every back facing polygon XOR in 1 into the B
  field

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The Vertex Hash Table
Vertex VFB VFB VFB VFB
1 200 300 400 500
2 300 500 X00 X00
3 400 500 X00 X00
4 500 X00 X00 X00
5 X00 X00 X00 x00
From Buchanan and Sousa
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The Vertex Hash Table
P1,2,3
Vertex VFB VFB VFB VFB
1 210 310 400 500
2 310 500 X00 X00
3 400 500 X00 X00
4 500 X00 X00 X00
5 X00 X00 X00 x00
From Buchanan and Sousa
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The Vertex Hash Table
P1,3,4
Vertex VFB VFB VFB VFB
1 210 300 410 500
2 310 500 X00 X00
3 410 500 X00 X00
4 500 X00 X00 X00
5 X00 X00 X00 x00
From Buchanan and Sousa
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The Vertex Hash Table
P3,4,5
Vertex VFB VFB VFB VFB
1 210 300 410 500
2 310 500 X00 X00
3 411 501 X00 X00
4 501 X00 X00 X00
5 X00 X00 X00 x00
From Buchanan and Sousa
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The Vertex Hash Table
Silhouette(1,2),(2,3),(3,4),(1,4)
Vertex VFB VFB VFB VFB
1 211 300 411 500
2 311 500 X00 X00
3 411 500 X00 X00
4 500 X00 X00 X00
5 X00 X00 X00 x00
Note (3,1) would not be drawn
From Buchanan and Sousa
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NPR Quake

• Intercept OpenGL calls so that the rendering
  style can be implemented independent of the game
  engine