I just spend ages carefully modelling a plane to match actual real-world terrain, for the sole purpose of having a shadow look natural as it moves over the eneven surface. Now I can't seem to figure out ho to render ONLY the shadow cast from the moving object. I was planning on using a surface shader, but I just realised they don't receive shadows from anywhere unless I'm mistaken. Turning off "casts shadows" on the surface, doesn't stop self-shadows. Isn't there a shadow linking editor like the light linking one, that determines which objects may cast shadows onto which?
I'll be comping into live footage, so I can't have the self shadow there. I'm almost tempted to just render with all the self-shadow, and just animate a mask around the shadow in AE. It's fairly diffuse so, with a feathered mask, it might be the quickest way. I just assumed Maya would have a one-click solution for things like this. Or are people comping shadows cast onto perfectly flat planes into live footage?