Hi, i have a scene where i have 2 objects with lights pointing at them giving them shadows on a plane. I have ambient occlusion and global illumination enabled. I also have a multi pass for gi and ao set up. My question is how can i render out the objects without the background but keeping the shadows on the plane? I tried before and i used the object buffer for the objects but just got an alpha channel for them, but did not know what to do after that. And i could not figure out how to get the shadows without the plane. Any help would be appreciated.
You may be able to use the multipass functionality to generate the required shadow passes. Depending on your need you could then either multiply them into the background you're compositing onto or maybe generate an alpha from them (mileage may vary).
You could also look into the Compositing Background setting on the Compositing Tag. It doesn't generate an alpha but it may be useful to you.