cs 395: adv. computer graphics

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

This is NPR:This is NPR:Non-Photorealistic RenderingNon-Photorealistic Rendering

Jack TumblinJack Tumblin

jet@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 offer us? Can we help What can artists offer us? Can we help them?them?– 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 on works of artmachine learning on works of art• analysis of working artistsanalysis of working artists

• What can we learn from What can we learn from the human visual system?the human visual system?

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 Pencil Observational Model of Graphite Pencil Materials.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)

..

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 Book:Great Book:

“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