View Full Version : 1 shadowmap in multiple lights

06 June 2002, 04:56 PM
as u saw in the topic i have a question regarding this.
a short time ago here was a user meeting where some guys from pixar talked a bit about their lighting in monstens inc. one thing they mentioned was that they were using one shadow map for multiple lights so they can place the lights in different positions without overlapping shadows, but i alwas thought that the shadowmap is calculated like a camera and only works from one position.
they are using renderman.
mayabe somebody of you can help me out.

thanks in advance

06 June 2002, 09:01 PM
difference is you are thinking of raytraced engines where IXAR is a reyes rendered (renders everything your eye see.) they are fuly programmable, every reflection is manipulated, not raytraced, so in some ways they can be less accurate, but its all in the hands of the artist.

06 June 2002, 11:13 PM
i tried it with mayaman and entropy. for my surprise it worked like i ever wanted it.
you can load a map into multiple lights without any overlapping of the shadows

06 June 2002, 04:59 PM
Of course you can. The light (resp. camera) transformation is written into the shadowmap file.
Read the coursenotes from Siggraph '99 at about the uberlight shader. It's basically a copy of the resp. chapter in the ARMan book and contains some intersting hints on using lightshaders that make the lights in MAX/Maya/Lightwave etc. seem like toys.

REYES btw means renders everything you ever saw.

90% of all blockbuster visual effects of the last decade have been rendered using PRMan from Pixar which happens to be a REYES renderer as of this writing.
As you see, fancy raytracing- and GI stuff is not neccesarily needed to fool the audiende.


06 June 2002, 11:55 PM
thanks for correcting the REYES acronym, I knew something other than my atrocious spelling looked wrong. And good point about REYES renderers, which is why I was surprised to see Pixar add Raytracing and Montecarlo GI, looks like they might have been noticing a little (very little) pinch in the dact that the render engines are getting better and faster, as well as computers, meaning they can start to compete with Renderman and the likes.

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