CS 395: Adv. Computer GraphicsCS 395: Adv. Computer Graphics

This This is NPR:is NPR:

Non-Non-Photorealistic Photorealistic RenderingRendering

Jack TumblinJack Tumblinjet@cs.northwestern.edujet@cs.northwestern.edu

Big Ideas in NPRBig Ideas in NPR

• What is the goal of computer graphics?What is the goal of computer graphics?– ‘‘A perfect simulation of light transport’? No...A perfect simulation of light transport’? No...– ‘‘The best picture for every task’ ?The best picture for every task’ ?

Optical Optical ImagesImages(photos, etc.)(photos, etc.)

All Great PicturesAll Great Pictures

Drawings,Drawings,illustrations,illustrations,paintings...paintings...

Fine Art

Fine Art

Big Ideas in NPRBig Ideas in NPR

• What can artists teach us? What can artists teach us? – Imitation (theft): Simulate existing artistic mediaImitation (theft): Simulate existing artistic media

• paint, charcoal, pencil, watercolor, marble, …paint, charcoal, pencil, watercolor, marble, …– Imitation (theft): Simulate artistic conventionsImitation (theft): Simulate artistic conventions

• ‘‘learn to draw’ bookslearn to draw’ books• machine learning machine learning

on works of arton works of art• analysis of working artistsanalysis of working artists

• Can we help them?Can we help them?• What can we learn What can we learn from human vision?from human vision?

Simulated Watercolor (1997)Simulated Watercolor (1997)

Simulate paper, water, fluid diffusion/soaking, drying,...Simulate paper, water, fluid diffusion/soaking, drying,...

““Computer Generated Computer Generated Watercolor”Watercolor”Curtis,Anderson, Seims, Curtis,Anderson, Seims, Fleischer,Salesin Fleischer,Salesin SIGGRAPH`97SIGGRAPH`97

Simulated WatercolorSimulated Watercolor

Faster: blots/splats...Faster: blots/splats...

Pen-And-Ink: Winkenbach et al 1994+Pen-And-Ink: Winkenbach et al 1994+

Pencil Simulation: Sousa 2000Pencil Simulation: Sousa 2000

Sousa, M. C. and Buchanan, J. W.Sousa, M. C. and Buchanan, J. W.Observational Model of Graphite Observational Model of Graphite Pencil MaterialsPencil Materials..Computer Graphics Forum, Computer Graphics Forum, 19(1):27--49, 2000.19(1):27--49, 2000.

Oil Painting SimulationOil Painting Simulation

• ..

‘‘Toon’ ShadersToon’ Shaders

Long history;Long history;

Levoy’77,Levoy’77,

......

NPR Quake Shaders (real time)NPR Quake Shaders (real time)

..Gleicher 2000Gleicher 2000

NPR Quake Shaders NPR Quake Shaders

M. Gleicher (U. Wisconsin)M. Gleicher (U. Wisconsin)

• Cool student projects gone wildCool student projects gone wild

• Downloadable, modifiable, try it!Downloadable, modifiable, try it!

http://www.cs.wisc.edu/graphics/Gallery/NPRQuake/whydWeDoIt.htmlhttp://www.cs.wisc.edu/graphics/Gallery/NPRQuake/whydWeDoIt.html

3D-Guided, Semantic NPR3D-Guided, Semantic NPR

Kowalski et al, “Art-Based Rendering”Kowalski et al, “Art-Based Rendering”

SIGGRAPH`99SIGGRAPH`99

Artistic Styles: Herzmann2000Artistic Styles: Herzmann2000

Machine learning,Machine learning,

Image analogies, etc....Image analogies, etc....

Artistic Styles: Herzmann2000Artistic Styles: Herzmann2000

Machine learning,Machine learning,

Image analogies, etc....Image analogies, etc....

More NPR ResourcesMore NPR Resources

• Great on-line surveys / tutorials: Great on-line surveys / tutorials: Craig ReynoldsCraig Reynolds

http://www.red3d.com/cwr/npr/http://www.red3d.com/cwr/npr/• Great Books:Great Books:

“Non-Photorealistic Rendering”Non-Photorealistic Rendering” (2001) (2001) Bruce Gooch and Amy Gooch, AK Peters Bruce Gooch and Amy Gooch, AK Peters

• Great Conference:Great Conference: ACM NPARACM NPAR: Non-Photorealistic Animation and RenderingNon-Photorealistic Animation and Rendering

• Great Online Demos:Great Online Demos:Google finds most of them...Google finds most of them...

• Great Papers: Great Papers: http://citeseer.nj.nec.com/cshttp://citeseer.nj.nec.com/cs