Wouldn't it be more efficient to just duplicate the layer and mask it out, then slightly move it to cover up the black spot? You are over-complicating this.
If anyone can help me understand how you solve these problems, like taking out a small flying bird. Birthmarks on skin when moving.
I usually like to to painting on moving objects inside a stabilized precomp.
You can create these either with mocha / MochaImport+
or, if you don't want to switch to a separate application for tracking you can do it with the mask tracker and MaskTracker+
I agree with Mylenium. You are way over thinking this. If you have CC2014 then use the mask tracker. Set up your comp like this:
- Drop your footage in a new timeline
- Duplicate the footage twice
- Draw a very small mask around the blemish that is only about twice the size of the blemish on the top copy of the footage
- Track the mask
- Add a tiny bit of mask feather
- Set the top copy as an alpha track matte for the second layer
- Since the blemish moves diagonally down and to the left move the second layer up and to the right until the blemish dissapears
If you don't have mask tracking then do this:
- Duplicate your footage in the tilmeline
- Track the blemish in the top copy with AE's point tracker
- Add a blue solid to the top layer and set the blend mode to screen so you can see through the solid
- Draw a small mask around the blemish
- Apply the tracking data to the blue solid
- Set the blue solid as a track matte for the footage below
- Follow the same logic in step 7 above
Like my friend Mathias I also do a lot of this kind of stuff by stabilizing a shot and then removing the stabilization with a null and an expression. Most of the time I just use AE's built in Stabilizer and stabilize position scale and rotation. I use it so much that I have created an animation preset. Because of the changing light on this shot the above methods will work much better and faster.