Nonphotorealistic rendering

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Nonphotorealistic rendering

• Computational Photography, 6.882
• Bill Freeman
• Fredo Durand
• May 9, 2006
• Drawing from NPR Siggraph 1999 course, Green et
  al. npr_course_Sig99.pdf

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Photorealism

• Physically realistic computer graphics rendering
• Images with photographic quality (eg Vermeer,
  1632-1675, accused by critics of being cold,
  inartistic, and displaying spiritual poverty).

http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
3
Are these images non-photorealistic renderings?
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
4
Non-photorealistic rendering

• Expressive, artistic, painterly, interpretative
  rendering.
• Not aspiring to realism.
• Early work natural media emulation
• Pen and ink
• Watercolor
• Oil on canvas
• Attempts to capture the low-level style.
• Simulations of technical illustration.

http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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NPAR 2002
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Comparing photorealism and NPR (Stuart Green)
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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(No Transcript)
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Statistical techniques to simulate expression
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Paintings are not solutions to well-posed
problems
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Daniel Teece
http//pages.cpsc.ucalgary.ca/mario/npr/projects/
sigg03/lec8/hand_1.pdf
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Organization of NPR methods

• Automated methods
• 2-d processing
• 3-d processing
• Interactive methods
• 2-d processing
• 3-d processing

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Organization of NPR methods

• Automated methods
• 2-d processing
• 3-d processing
• Interactive methods
• 2-d processing
• 3-d processing

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2/2.5 D, no user intervention
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.mrl.nyu.edu/publications/hertzmann-thes
is/hertzmann-thesis-72dpi.pdf
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Issues in image style translation

• Fitting
• Translation

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http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input traced line drawing
This example will illustrate the tension between
fitting and translation
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
1-NN fit to input, style 1
Translation to style 2
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
1-NN fit to input, style 1
Translation to style 2
Bad fit, good translation
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
5904-NN fit to input, style 1
Translation to style 2.
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
5904-NN fit to input, style 1
Translation to style 2.
Good fit, bad translation
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
6-NN fit to input, style 1
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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Input drawing
6-NN fit to input, style 1
Translation to style 2
Good fit, good translation
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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style 1
style 2
style 3
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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6-NN fit to input, style 1
Translation to style 3
http//people.csail.mit.edu/billf/papers/p33-t_fre
eman.pdf
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http//mrl.nyu.edu/projects/image-analogies/
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http//mrl.nyu.edu/publications/image-analogies/an
alogies-72dpi.pdf
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Image analogies applications
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For painterly style translation, how get the A,
A image pairs?
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http//mrl.nyu.edu/projects/image-analogies/
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http//mrl.nyu.edu/projects/image-analogies/
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http//mrl.nyu.edu/projects/image-analogies/
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Texture Transfer

• Take the texture from one object and paint it
  onto another object
• This requires separating texture and shape
• Thats HARD, but we can cheat
• Assume we can capture shape by boundary and rough
  shading

Then, just add another constraint when sampling
similarity to underlying image at that spot
http//people.csail.mit.edu/billf/papers/efrosFree
man.pdf
37
Source texture
Target image
http//people.csail.mit.edu/billf/papers/efrosFree
man.pdf
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http//people.csail.mit.edu/billf/papers/efrosFree
man.pdf
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A
A
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(No Transcript)
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B
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B
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B
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I think this one fails
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Organization of NPR methods

• Automated methods
• 2-d processing
• 3-d processing
• Interactive methods
• 2-d processing
• 3-d processing

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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Gooch and Gooch

• Concentrate on the material property and shading
  aspects of technical illustration.

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Some characteristics of technical illustrations
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
51
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Technical illustrations

• Lines

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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Some parameterization dependent lines
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Line weight variations
Line weight varied to emphasize perspective
Outer edges thicker
Equal weight
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Technical illustrations

• Shading

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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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(No Transcript)
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Encoding surface orientation by color temperature
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Direction dependent illumination color
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Combining color-temp surface orientation coding
with some tonal variations in object color
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Parameter setting 1
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Parameter setting 2
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Metal object with anisotropic reflections
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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Metal object with anisotropic reflections
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
Lines are streaked in the direction of the axis
of minimum curvature, parallel to the milling
axis.
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf
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3D, little user intervention
http//www.cs.utah.edu/npr/papers/npr_course_Sig99
.pdf