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Need to pan-behind to slide a solid with already roto’d mask
Okay, I’m working on a roto shot. I’ve created a solid and drawn my mask on that to use as an alpha track matte above my footage. The problem is, now that I’ve done about 20 keyframes on the mask I notice that the motion-tracked solid slides off my footage. The mask is perfect, but the solid is not where it should be. So I need to pan-behind the solid and keep the mask where it is. I’ve tried clicking the mask shape property to select all it’s keyframes, then using the pan-behind tool to slide the solid over. This works for whatever keyframe I am on, but the other keyframes don’t seem to be affected. Is there a way to do what I’m trying to do without realigning each keyframe? Thanks.
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3 Replies
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[Robert Morris] “The mask is perfect, but the solid is not where it should be”
I’m confused, if the solid with the mask on it is being used as an alpha matte, shouldn’t you just be able to change the transform properties of the solid to change the location of the matte? Perhaps I’m not entirely understanding the issue, if I’m way off base could you clarify the problem?
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA -
Okay, let me try to clarify. I have footage of a man’s head. The head is moving around the screen for the duration of the shot. I have a white solid tracked to the head. I’ve drawn a mask on the white solid to trace the contour of the head. But the head moves so much that the white solid isn’t covering the top of the head when it comes into frame, essentially creating a cut in my alpha where the solid ends. Yet I’ve already adjusted my mask on the first part of the shot for about 20 keyframes. If I pan-behind to move the solid to cover the top of the head, it only pans behind on the mask keyframe I am currently on and not on the rest of the shot. So I’m wondering if there is a way I can slide the solid up to cover the top of the head, yet keep my already drawn mask where it is… essentially doing a pan-behind, but having it effect all mask keyframes the same.
https://www.mechanicalwhispers.com
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[Robert Morris] “So I’m wondering if there is a way I can slide the solid up to cover the top of the head, yet keep my already drawn mask where it is… essentially doing a pan-behind, but having it effect all mask keyframes the same.”
I don’t think this is possible the way you’re attempting it. If I understand you the issue is that the solid is not big enough for the area that the mask must cover. If this is the case then try the following solution:
1) Pre-compose your solid and leave all attributes in your main comp.
2) Enable collapse transformations on the pre-comp.
3) Inside the pre-comp scale up the white solid something like 200% (but don’t change the size of the comp!)
4) In your main comp you should see that the solid now extends beyond the boundaries of the pre-composition and the masked area is now fully solid.
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA
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