Real Photo Environment

[danf]

I found photos of the exact desert I want represented in my animation, and I feel humbled by the number of subtle shrubs, hills, bluffs, and so on that make the desert what it is. Especially since it is only going to be in the background and does not move, I don't see the sense in modeling all of this from scratch.

 

So now I'm toying with the logistics of animating my A:M components to be most compatible with my photoshopped and then 3-D composited (probably in After Effects) sort of environment.

 

I understand there's a way to render animations with an alpha channel, although I don't know how. I guess that's question number one.

 

Another question is "how to cast shadows that also preserve this alpha layer, so they will be cast on whatever the animation is later composited upon?"

 

I was experimenting with giving the ground a texture map of the desert I wanted, but here was my catch: I have photos from the angle I want represented. I was hoping to texture map the ground layer at that angle, so the perspective would be relatively preserved. But to apply a decal I have to leave the choreography for the modeling mode, which strips me of the context I was using to get the perspective right. Any tips on achieving this effect?