render elements behind transparent objects

[Matt McDonald]

Using render elements I am trying to get a object ID pass or MR Labeled Element pass to include object which are behind glass. If you look at the attached images you will see what I am talking about. You can see in my beauty pass I have a row of teapots behind a piece of glass. In the object ID pass only the first tea pot is partially shown and the rest are obscured.

 

I see that I could hide the glass, render and then render again with the glass but I'm really trying to do it all in one pass. Any suggestions would be much appreciated.

 

Cheers

Matt

[BrianKitts]

are you using Mental Ray? I'm not sure what a MR labeled Element is....

 

In vray you have to have the affect shadows option set to all channels in the glass material to fix this problem.... perhaps it's something in the glass material settings?

[Matt McDonald]

I am using Mental Ray. An MR Labeled Element is a render element which will mask materials which have a certain shader applied to them. The problem doesn't seem to be specific to that render element though. Material ID and Object ID elements produce the same problem.

 

The affect shadows option in V-Ray eh? That's the option you have to enable if you want any exterior light to get inside your building right? I'm not sure that MR has a similar option. I have Transparency propagates Alpha channel but that does not seem to affect the render elements, only the alpha for the beauty pass.

[Justin Hunt]

I have done this by rendering a separate pass with the transparent object as grey and everything else as black, then use this as the alpha. Of cause you will have to render the teapot and glass separatley.

 

Not the most elegant solution but it worked for me

 

jhv