How to subtract mask over a screencast

Please refer to the attached image.

I have used the planar tracker to track a video onto a picture in my room. My hand covers the video that is being tracked to the picture for a few seconds. How can I create a mask to remove part of the video where my hand covers?

Thanks.

You'll need to Roto the hand, quite possibly frame by frame.

You'll need to Roto the hand, quite possibly frame by frame.

Thanks for your help. There's no way to use a tracker instead of frame by frame? Would you mind telling me what Roto is, or linking me to some resources?

Search Roto-Scoping for an overview. And in Resolve 17 there's a new "Magic Mask" tool that may be helpful. In general though there's usually some manual work involved.

It's usually a good idea to plan out a workflow before filming. Best practice would be to use a pure green/blue card in the picture frame when filming. You can then use your tracking plus chromakey to matte out around your hand. Much easier that roto frame by frame.

It's usually a good idea to plan out a workflow before filming. Best practice would be to use a pure green/blue card in the picture frame when filming. You can then use your tracking plus chromakey to matte out around your hand. Much easier that roto frame by frame.

Yes, Gary nails it. This is what I always do as well. But don't be discouraged roto-ing a short simple clip isn't too bad.

Create planar transform from the planar tracker that you have already used to track the picture, create a polygon roto mask, connect it to the planar transform, and then connect to the merge node as mask input. Start drawing the roto mask for the hand in the polygon node, invert mask if needed.