Glass Map From framebuffer

[Daniel Doerksen]

Would it be possible to create a map similar to the alpha map that mask out windows for post process compositing. like a creating a render element for it?

[maciejwypych]

Would it be possible to create a map similar to the alpha map that mask out windows for post process compositing. like a creating a render element for it?

 

U can render refraction map (select from render elements) and use it as a mask to select the windows.

[Nic H]

dont use refraction - it wont give you a proper matte.

you need to use a multimatte render element and use object ID to assign r,g,b to the corresponding id.

then in post you can get a proper clean matte!

[Stephen Thomas]

I agree with Nic. I find the easiest way to set it up is per material rather than object though. Just go to your glass material and change the material ID from the default zero to 1. Then in your Multimatte make sure you have selected channel 1 and checked the Material ID box. You can set up to 3 different materials per pass, and you can have as many different multimattes as you like, giveing you great control over changes in post.

 

To select the channel properly in Photoshop DO NOT use select by color range! Isolate the Multimatte layer then ctrl+click on the relevant channel to get the selection.

[Daniel Doerksen]

thanks guys that works perfectly