About Pixar's RAT (RenderMan Artist Tools)

[nicla]

HI,

I have a question, a friend just told Renderman artist tools from pixar for maya does not do raytracing at all. What's that deal with that? I mean how do you raytrace something then? How does pixar does it?

[goesb]

Don't know about Renderman but I don't think pixar would use raytracing. Most studios won't use raytracing, caustics and radiosity, they're too taxing on any system. They would just fake it.

[nicla]

So if they have a animation project you tell me they will fake it frame by frame?

[surfacesurfer]

BMRT..a rendering program that uses the .rib (renderman) format supports raytracing. I believe the man who invented it now works at Pixar. I've used it a decent amount, and it's renderings are beautiful, and the speed is pretty incredible when you weigh it out to the quality and raytracing (as well as caustics, radiosity etc.). Check it out.

www.BMRT.org

Eric

[tito212]

You are correct, PRMan does not raytrace. But if you are in IRIX land you can use BMRT as a 'ray server" for PRMan. Unfortunately, this functionality is not currently supported in the NT version of BMRT.

This feature was used in the movie "Hollow Man", probably in the pool scene.

adam...

[yellowsayshello]

Just to add to what's already here...Pixar themselves also used BMRT as a ray server for Toy Story 2 and A Bug's Life...apparently Pixar has only 3 seconds of raytracing in anything they've done so far.

Faking it does not mean drawing it frame by frame...it means they used an environment sphere or cube or a reflection map, or somehow simulated reflections or refractions with texture maps...they don't have to be accurate, they just have to look accurate.

10 PRINT "kemijo is the best"
20 GOTO 10

RUN

[nicla]

ok, thanks guys for the info but how would connect renderman and BMRT to render ? to work as a "one" render engine?

[mestela]

Get the book 'advanced renderman', it explains how to set this up in detail.

Don't sweat the lack of raytracing though, reflection/refraction mapping looks just fine 90% of the time, and the speed advantage is huge.

-matt

[jhazard]

They don't .
They just render different passes (shadows pass, reflection pass,specular pass etc.as much as needed) in each one and the composite the results in one picture in compositing program like Maya Fusion , Shake , Chalice , Composer etc (it's a users choice).