[Sidefx-houdini-list] rectangular pbr area light

Mario Marengo mario at axyzfx.com
Fri Dec 7 11:05:09 EST 2007


On December 7, 2007 09:13 am, Luc Froehlicher wrote:
> is it possible to have rectangular area light (H9 PBR) ?
> luc

If what you want is a *square* area light (not rectangular), then you can use 
an area light set to "Grid". You can choose among several basic symmetrical 
shapes with this approach, and it works in every rendering engine.

If you want an actual rectangle, or some other arbitrary shape, then create 
the emitter geometry and assign it a constant shader (vex_constant will do), 
then make sure your ROP's "Diffuse Limit" is set to 1 or higher, else you 
won't get a diffuse contribution (Glossy Limit defaults to 1 I believe, so 
you'll get one bounce of specular, but no diffuse, by default).
Anyway, I guess the main point is: assigning a constant value (as opposed to 
bsdf) to the global F in a shader is equivalent to defining an emitter with 
the given value as its power.
Also, you'll likely need to raise "Pixel Samples" in the ROP to something 
higher than default to reduce sampling noise.


-- 
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Mario Marengo                                  mailto:mario at axyzfx.com
AXYZ ANIMATION                                 http://www.axyzfx.com
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