I am creating a 3ds Max scene composited with a piece of footage I keyed in After Effects so that it has an Alpha channel. The footage is saved as a Targa sequence with an Alpha. My problem is I have this footage applied to a plane in my scene but I don't get the correct shadows. I am using a "Matte/Shadow/Reflection" Mental Ray shader and the areas that are transparent in the footage display correctly but the shadows cast are of the entire plane (not just the opaque areas from the footage). Why is this? I am using RayTrace shadows for all my lights, so shouldn't the shadows be that of the footage's opaque areas? Why is the entire plane casting a shadow?
Another side question, I originally tried just a Standard shader with a Bitmap, selected the “Alpha” for “Mono Channel Output”, and “Image Alpha” for the “Alpha Source”, but I didn’t get any transparency. Any one know why the Alpha area didn’t go transparent?
Thank for any help. I am very close to completing this scene, I just need this footage in there.