Vray properties Matte problem

[Kr0no]

Hi, i have a little problem with the vray properties.
(max2009 vray 1.5 sp2)Linear color space, gamma 2.2, Vray sun, physical cam,))

I use to do that a lot in previous build without any problem, i have a simple scene of a room with a couple of animated character, i want to render the scene then my character with the rest of the scene in matte,

Look at the image...


[URL=http://g.imageshack.us/img528/matteproboa1.jpg/1/][IMG]

Pic2 is the whole scene room+character, Pic 2 is the scene without the character, then i render my characters with the rest of the scene in matte,(1A) matte object tick, -1.0, shadows and affect alpha, the rgb seem all right but alpha is wrong, i have GI all over the scene wich i dont want and obviously.

Second render of the matte pass, pic2A, setting 2A, alpha is good but rgb is washed out and got color splotches, like there were no geometry in the scene and character get washed out by the outside sun, try to untick the No GI on other matte too and get same result as pic1A

Im not sure what im missing here, if anyone can help.

Hope im clear enough, if not sorry for my bad english!
thanks

Kr0no

[vlado]

You could try to turn off GI for the matte pass, as it appears you don't want it anyways. If you do want to use it, you will need to adjust your GI environment to get the desired strength of the GI in the alpha channel.

This is because V-Ray takes the actual calculated GI, compares is to the GI environment (in the V-Ray::Environment dialog, if this is switched on, or the 3ds Max Environment dialog otherwise), and takes the difference between them as the GI alpha shadow for the matte objects.

Best regards,
Vlado

[Kr0no]

Thx for the answer Vlado, I have a vraysky in the envirronement roll out on, I cant just turn it off? If i do i get some weird render and my character are still washed out. Is there a way to calculate myscene with the GI, then the scene in matte -1.0, and my character with the GI too?

Regards

Kr0no

[vlado]

You can try to set the "GI amount" in the V-Ray matte properties to 0.0 and see if it helps, but I think the correct way of doing this would require more passes on the image to get it right.

Best regards,
Vlado

[vlado]

Ah, also another option might be to use a dome light with the VRaySky inside it; in that way you can control the background GI color separately without it affecting your image.

Best regards,
Vlado

[Kr0no]

I tried to shut off the vraysky in the env rollout, No help there and either the other solution, i guess i will have to render the character the old way, omni around to simulate ambiant light and no gi, the rest of the scene with matte -1.0.

regards

Kr0no

[RErender]

Why not render Pic1A for the diffuse pass and Pic2A for the alpha?

[Kr0no]

i thought about it rerender, but thats 2 render, and i have to optimize my rendering because we dont have a big render farm and a lot of frame to output! Worst case i could go that way, thx anyway!

regards

Kr0no