ok so i have a scene with a car model, a curved plane for the floor/backwall, and a sphere with a HDR image on it for lighting and such, i'm trying to render it so that the floor/backwall and the sphere aren't there so i can composite it over a preexisting image in PS. i need the lighting and reflection info from the sphere but not it visibility it the background, and i need the shadows on the floor but again not it's visability anywhere, i'm running maya 2008, any help would be awsome thanks in advance