I'm working on an A:M project at work and I have to create my *very first* alpha channel. I'm rendering out as a series of targas and I've noticed that they automatically generate an alpha channel when I open them in Photoshop, but by default the alpha is a blank screen, so I need to figure out how to silhouette just the main elements, However I think I've created a problem for myself before I've even left the gate.

Can an alpha channel silhouette only one part of a model? I need to silo the infamous laptop computer and its cast shadow. But in order to solve another problem, I had deleted the default "ground" from the chor and included a ground plane as part of the laptop model. Now of course I need to silo just the laptop for the alpha channel so I think I've screwed myself.

However I also don't see where you select elements to be separated out by the alpha, so I don't actually know what I'm doing.

Any help will be appreciated.

Gerry