Alpha maps and VRay

[mindrot]

Hi there....

I'm trying to set up a VRay material with alpha maps (using one TGA with an embedded alpha channel). What I have is lowpoly hair that has been alpha mapped. But the transparent areas are showing up grey (at render time) when I use VRay materials.

The problem is I cannot get the alpha to render. It works fine with normal Max materials, but not with VRay's.

This is all it says in the VRay help file: Note that your lights must have VRay shadows for translucency to work. Glossy must be turned on too. VRay will use the Fog color to determine the amount of light that passes through the material below the surface.

Can anyone help me out? Are there any tutorials for this as it should be really simple to do (like max's standard materials), but seems to be a bit of a nightmare. I have yet to find a solution

Pleeeeease....

[Biohazard]

You should have a look at this entry.
http://www.vray.info/entry.asp?entryID=91

[RErender]

Vraymtl uses refraction for opacity...

Your map should be in the refract slot, set the ior to 1.0. In the bitmap paramaters check "alpha as gray" and "invert" in output.

Hope this helps.

[RErender]

I was typing slowly while biohazard posted his, I think that entry in vray info is a bit outdated, Should still work though

[Biohazard]

Yep, the same here.
I guess the 'affect alpha' option would do the trick.
The link I gave was working when ior=1 did not solve the transparency problem.

[mindrot]

Thanks all

Most appreciated. I also saw that link the other night. I tried it bit couldn't get it to work. I must be doing something wrong.

I tried this that someone pointed out to me at CGTalk, but still had no luck So somewhere I am getting something wrong:

? Use blend material
? use your tga opacity map in the mask slot
? in the 1st slot your color or bitmap
? in the 2nd a Vray mat wrapper as a shadow matte option.

Does any one have quick step by step solution?

Thanks

[Biohazard]

Exactly.
Be sure of 2 things

1) that your bitmap is effectively controling the blend by luma and not by alpha
2) That your mtlwrapper is set to alpha contribution -1

[RErender]

The way I mentioned works perfectly, but if you guys like the hard way, go for it