If I use color range key, is it possible to create a mask from the matte around the object without using the pen tool? I want the mask to follow the object as it moves in the clip.
Pre-compose the keyed result, use the auto-trace function in the parent comp.
Thanx Mylenium, you are always helpful! Is there a tutorial for this?
I tried the auto-trace and its fine, but the new mask does not move with the clip?
I have worked now with auto-trace and there is two different settings, "current frame" or "current workspace" and in my case, working with a clip, the correct setting is the later.
If you don't need a vector path, all you have to do is use Set Matte to create transparency from any layer with high contrast or clarity. Color Range Key should have given you an Alpha Channel (transparency). You could use that on another layer with Set Matte, then Auto-trace the other layer or maybe Pre-compose the original layer and use Auto-trace on the new nested pre-comp.
Unless you are running out of resources for Auto Trace because of too many details or incorrect settings, Auto Trace should work for you.
But can autotrace be used on moving objects in clips? What I can see the mask is not following my clip, just forms around the first frame, its static?