NPR Nonphotorealistic Rendering

1
NPR(Non-photorealistic Rendering)

• Billy Davidson
• CS 395 Advanced Graphics
• January 22, 2004

2
Non-photorealistic Rendering

• Most computer graphics work strives for
  photorealism
• Other types of depiction can be more expressive
  or artistic
• Depict intrinsic or extrinsic properties?

3
Terminology

• Image
• Picture
• Intrinsic/Invariant
• Extrinsic
• Constancy

4
Constancy

• We do not experience some extrinsic properties of
  the image we see

5
3D -gt 2D Mappings

• Sketches by 7-year old children

6
Depiction

• Depiction is the mapping of properties of the
  scene to properties of the picture
• Traditional 3D -gt 2D geometric projection is only
  one possible meaningful mapping

7
Projections

• Different projections preserve different
  intrinsic properties

8
(No Transcript)
9
Vision as Inverse Problem

• V() Visual reaction function
• Not invertible due to ambiguity, emotional
  factors, etc.

10
Primary vs. Secondary Space

• Respect local rules but not global ones

11
Primary vs. Secondary Space

• Tone mapping

12
Representation Systems

• Spatial system
• Primitive system
• Attribute system
• Mark system

13
Painterly Rendering

• Tarzan

14
Pen Strokes

• Bones

15
Cel Shading

• The Legend of Zelda The Wind Waker