Hey,
So I was following an old tutorial that used Blender internal and trying to recreate it in cycles. Basically I have a tracked shot and a cycles model that I want to incorporate into my scene. It’s successfully tracked and the model is there but I cant seem to composite in a shadow plane. I have been partially successful but my plane still remains in the scene and makes the background footage darker.
Looks like your shadow pass isn’t 100% white. Add a ColorRamp node directly after the Shadow output and bring the white slider inwards until the grey plane in your image disappears. You may have to tweak the Color Ramp settings a bit to get the objects shadow just right.
Agree with hype but you shouldn’t have to use a ColorRamp to boost the white : it seems that few factors make your shadows grey and not pure back/white :
The best results I’ve had with cycles shadow planes have been using a slightly more complex setup. Render 2 layers of the shadow plane, one with the influence of the fg object excluded, then subtract them and invert. This gives you a pretty decent shadow-only that you can comp and tweak.