Matte properties not working correctly on glasses

V-Ray V-Ray for 3ds Max Issues
1

Hello,

I am having trouble with matte objects. I usually set mattes in vray properties, checking “matte object” alpha contribution -1, and checking “shadows” and “affect alpha”. I expect that objects with this options avoid the visibility of other objects behind them acordding the refraction, for example if the matte object use a 0% refraction material, then nothing is going to be visible behind it, but if matte object use a 50% refraction material, then, objects behind will be 50% visible. My problem is that all objects works the same… as if they have 0% refraction and glasses are not working as glasses. Is there any option I am forgetting?? My glass material is simple: difusse: gray color, reflection 35, refraction 225, affect shadows checked and in “affect channels” I am selecting: color+alpha (I am using max 2010 + vray sp4a). Thanks in advance for any help.

2

There is an option in the Matte settings, called “No GI on other mattes”, try turning it OFF and see if it helps.

Best regards,
Vlado

3

Vlado,

I still have the problem of people behind the glass. I put people moving in vray irradiance animation mode, if I matte all the scene except the lowpolys the people behind the glass just dissapears (or the ones behind a glass railing are cut from the waist down)
Is there any solution to this?

Best,

Gonzalo

4

The same here… and the “No GI on other mattes” option does not make any change…

5

I’m not sure matte objects can help you at all in such cases (they were not designed for this). Using VRaySphereFade might be more successful, but it all depends on what exactly you are trying to do.

Best regards,
Vlado

6

Lets say that you have a real photo of a whisky glass, and you want to add som CG whisky?
I’m trying this right now, and i cant figure out how to do it.
I have modelled the glass like it is in the photo, and added a glass material to it.
I’ve added the whisky in the glass, so a part of it is visible directly to the camera, and part of it is seen through the glass.
Now i want to render out only the whisky, but with the refractive effect from the glass. (IOR higher than 1)
If i set the mtlwrapper to matte surface=on, alpha=-1 ,shadow=on, affect alpha=on, then the whisky that is behind the glass doesn’t show.
If i set alpha=0, then the part of the whisky that is behind the glass, looses its refraction.

What would be the best way to do this?