[Sidefx-houdini-list] rectangular pbr area light
lulu at alamaison.fr
Fri Dec 7 12:03:44 EST 2007
Mario Marengo a écrit :
> On December 7, 2007 09:13 am, Luc Froehlicher wrote:
>> is it possible to have rectangular area light (H9 PBR) ?
> 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.
well I need to mimic kino flo's type of light.
I noticed that if I edit the interface there's a parameter vm_areasize
(2 floats array) but it doesn't seem to have any influence.
> 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.
I tried that and increased the diffuse value but , as you say , it's
very noisy :(
thanks for helping.
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