Blackmagic Forum

Hi,

I've looked into this on the forum and manual, but still not sure on how to handle the following:

Say I drawn a polygon window on a part of the footage and tracked it.
But during the shot the window, for a few frames, is covered by something in front of it in the shot.
Due to this you have to tweak the window, or you cannot properly color correct it.
So..
- Can I animate the polygon points after tracking for the offending frames? I cannot seem to find this..
- Or do I have too create a second polygon window, track that too and subtract it from the first?

Just looking into the best workflow part of things here, still new to all this

rob

This video should help even though it is using Resolve 12.

Yes, Daria Fissoun's video above illustrates the problem.

In VFX, they have to worry about occlusion the issue where an object gets in front of the composite. In color, we have to deal with the same thing if we're changing color or brightness with a power window. The solution is to create a second window within the same node, track the other object, then use the MASK setting to allow it to move through the other window and not allow the first window to affect the shot. Sometimes it requires meticulous rotoscoping in order to make this as invisible as possible.

It takes more time to explain than to do, but it's an important part of understanding windows and nodes and how to create complex shapes and hide windows when necessary.

Thanks for the replies and the video!

I will dive into this a bit more to get things into a steady workflow.

And I assume it's not possible to keyframe the shape of a polygon power window then?
I may be expecting Fusion functionality here.

rob

What Marc wrote.

And whatever you do, don’t try to modify the shape of one object to match the edges of another. Always use separate shapes for separate logical objects (or their components) and use mask modes to combine them.

Hi,

Yeah, I already was used to multiple shapes for mattes etc, but with comping you can often keyframe the points of the shape too.
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cheers,

rob

You CAN keyframe the points on a power window. You use FRAME mode in the tracker.

You can keyframe them allright, but there are cases where you shouldn’t do it. A simple example from a popular youtube tutorial: hand moves over coffeecup and coffee is rotoed to do something with color or overlay a foam image or whatever. Tutorial shows reshaping the round coffee shape to match the outline of fingers as they intersect. NEVER do stupid things like this unless you feel like wasting time and doing stupid things. Create one shape for coffee, another for hand and animate the hand shape move.