Light Material with no alpha contribution on backside

[Wobi]

Hi there,

I need to have light material that does not contribute to the alpha channel of my rendering on the backside of faces. I have a hollowed cylinder, just thin geometry. So when I render I only see the portion of the polys that face the camera. However, the backfacing polys also contribute to the alpha channel. So I tried to create a Vray2Sided material with my light-material in the front channel and a materialwrapper (alpha set to 0) in the back channel, but that does not do what I need.
Can anyone help me out please?!

Greetz Ben

[Morne]

what happens if you have just a normal vraymtl assign and under options of the vray shader, untick "Double-Sided"?
sorry I can't test it myself right now to see

[svetlozar.draganov]

Turn ON Force Back Face Culling in Global Switches and you won't see back-facing polygons in the render.

[Zdravko]

You need to set VRayLightMtl in the Vray2Sided Back material (or Face), set the Translucency to white and make sure you have Emmit light on back side option enabled in the VRayLightMtl settings.
I hope this helps.