Making the World Alpha?

I am trying to create a 3d Glass frame and import it into Adobe After Effects for a Video that I a putting together. When I have done this before, with other solid objects, I have always gotten around this questions by making the World a color I could key out. Glass does not allow me to skirt the question any longer.

I currently create the object then render it to a raw avi file for input into After Effects.

Any help would be appreciated.


raw avi does not support an alpha channel. You have to use a PNG sequence with RGBA enabled.

I must be missing something. When I try to output the glass to PNG the glass takes on a color. If I delete the world color the glass turns black. If I add a world color the glass takes on that color.

well, yes. you are correct, for clear glass. When you layer that glass on top of whatever, the whatever will show through the glass, because the glass is transparent. If you want it like frosted, use a gray material and something like 0.1 alpha. Glass can be colored as well. If you want the glass to refract the image, then you have to put out the Refr-action pass in the renderlayer and save it and use it in AE.

As an alternative workflow, you can just use the background image as a background image in Blender, and just render it in Blender and not even use AE…

I was hoping there was a way to render this frosted tinted glass frame with highlights and all without blender putting in a background color at all. If the glass is clear I don’t have this problem. AE will key the background color out. When I start to add a tint is when the problem shows up. The background color that blender puts onto the frame mixes with the tint.

I think you already had it when you rendered with NO world, or a white world…or maybe a black one…or even a neutral gray shade, depending on how much frosting you want the glass to have. Not sure how or what you are mixing in the background, so it’s difficult to say exactly, but this example has a scene with NO world (click the X next to the world name in the material world settings), the cube is 50% alpha, with a cloud texture mapped to white for a little frosting


That works for me! Thanks a bunch!!