problem with vray light mat & material wrapper/matte sha

[highpoly]

I have a scene with a plane emiting a vray light material and that is the only light in the scene. I have no vray lights or env skylight (set to zero). I also have to have the ground plane accept shadows plus be visible to reflections and contribute to GI, but not be in the alpha since they want to change the background later. using a vray material wrapper (alpha cont -1.0, etc...)
With this one lightbox emiting GI light in the scene on a visible floor plane its fine, get shadows etc. but when i put a mat wrap to just get the shadows they arent there and i get an ilegal pixels (see below). interesting thing is if I add a vray direct light, the shadow are there using the mat wrapper. Is there some prob with using just GI light and the material wrapper/matte shadows? am i doing something wrong? can someone please help me with this?

http://www.geocities.com/highpoly/fo...r_visisble.jpg
http://www.geocities.com/highpoly/forum/floor_matte.jpg


thanks

[vlado]

For the matte shadow to work, the render engine needs to explicitly know what are the lights in the scene, so that it can compare a non-shadowed version of the scene agains a shadowed one. Obviously, to this end, it must specifically know what is a light source, and what isn't. However, the self-illuminated VRayLightMtl material does not provide this information.

Best regards,
Vlado

[highpoly]

thanks vlado..at least i know why now..
will the matte/shadow work with env skylight?
i am guessing it would..i will try that..

thanks!

[highpoly]

just FYI for anyone who has been reading, the skylight worked fine with the matte material, but I am sure most of you already knew that!

now there is just white env light, white env reflections, and a black tube surrounding the scene, invisible to GI, camera, cast and receive shadows. worked pretty well I think...alpha is fine too. here a render

http://www.geocities.com/highpoly/forum/6.jpg

[vlado]

Yes, skylight will work... V-Ray knows how to deal with it.

Best regards,
Vlado