Stupid RAT Tricks, Pixar User’s Group 2001

The RenderMan™ EasyBake™ Oven™

Stupid RAT Tricks, Pixar User’s Group 2001

The RenderMan™ EasyBake™ Oven™• Jonathan Litt (presenting)Jonathan Litt (presenting)

•Technical Director, ILM

• Dan GoldmanDan Goldman•CG Supervisor, ILM

Subject: how can I pre-light my scene using MTOR?Subject: how can I pre-light my scene using MTOR?

Date: 15 Aug 2001 09:05:13 -0700Date: 15 Aug 2001 09:05:13 -0700

From: harley@public1.ptt.js.cn (harley)From: harley@public1.ptt.js.cn (harley)

Newsgroups: comp.graphics.rendering.rendermanNewsgroups: comp.graphics.rendering.renderman

Hello, i am using maya with renderman. I Hello, i am using maya with renderman. I have a big scene with about 200 light. have a big scene with about 200 light. Nothing move in the scene. To speed up the Nothing move in the scene. To speed up the rendering, i want to convert all the light rendering, i want to convert all the light effects on the object to textures. I think effects on the object to textures. I think that mean "pre-light" . How can i do that.that mean "pre-light" . How can i do that.

Thank you very much for your help!Thank you very much for your help!

Shading Network ExampleShading Network Example

Texture

Noise

ColorAdjust

Bump

Lighting

Synthesis Color

Shading Network with BakingShading Network with Baking

Texture

Noise

ColorAdjust

Bump

Lighting

SynthesisBaked

TextureStub

bake

Color

The Phantom MeshThe Phantom Mesh

•RenderRender flattened flattened geometrygeometry•ShadeShade original original (phantom) (phantom) geometrygeometry

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

Case Study: A BagelCase Study: A Bagel

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

Original Render Baked Texture

How does it work?Part #1: RIB ModificationsHow does it work?Part #1: RIB Modifications• Regular rib:Regular rib:

PatchMesh “P” [<points> …]

• Replace vertices (Replace vertices (PP) with ) with s/t s/t coordinates:coordinates:(x,y,z) --> (s,t,0)

• Attach original Attach original PP as as PrefPref (reference (reference geometry)geometry)

• Baked rib:Baked rib:CoordSysTransform “NDC”

PatchMesh “P” [ (s,t,0) …] “Pref” [ <points> ]

• Render with orthographic cameraRender with orthographic camera

How does it work?Part #2: Shader Modifications

How does it work?Part #2: Shader Modifications• Do Do allall shading on reference geometry shading on reference geometry• Replace Replace PP with with PrefPref at beginning of shader: at beginning of shader:

point oldP = P;

P = transform(“object”, Pref);

P = transform(“world”, “current”, P);

N = calculatenormal(P);

• Restore P at end of shader:Restore P at end of shader:P = oldP;

• Beware of view-dependent shadingBeware of view-dependent shading

A Non-Leaning TowerA Non-Leaning Tower

•121 lights121 lights•Single patchSingle patch•Render time: 3.5 Render time: 3.5 minutes (resolution minutes (resolution 600x750)600x750)

Baked towerBaked tower

•Bake time: 15 Bake time: 15 minutes (1k x 1k)minutes (1k x 1k)

Rendered with Baked TextureRendered with Baked Texture

•Render time: 10 Render time: 10 secondsseconds•No more lights in No more lights in scenescene

Baking & AntialiasingBaking & Antialiasing

• Got aliasing? Can use baking to Got aliasing? Can use baking to oversampleoversample

• Only have to oversample once, then Only have to oversample once, then let texture filtering take care of the let texture filtering take care of the restrest

Next Year:

Using RenderMan to Bake DeliciousShortbread Cookies with Sprinkles

Next Year:

Using RenderMan to Bake DeliciousShortbread Cookies with Sprinkles