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Parenting to a mask – HELP!
Hi, Cowsters:
I am trying to create the illusion of a tennis ball in a glass moving inside the glass as someone picks the glass up to drink. The tennis ball should parent the movements of the glass. On one layer, I have the tennis ball (background cut out with the color key). On the other layer, I have the glass of water with its background. I have created a mask of the glass of water as it is moving. back and forth, up and down. Now what I want to do is parent the tennis ball layer’s movements to the movements of the glass of water mask. I already tried parenting to the layer, but the tennis ball doesn’t move, and I don’t know why. I suspect I have to do something with the anchor point of the glass, but I am not sure.
How do I parent this object to the mask so that its movements are smooth? Is there a better way to do this than creating a position keyframe every frame?
Muchas gracias,
OMU -
3 Replies
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I think you’re going about this the wrong way. You should use the ae tracker to track the position of the glass. However, if it is tilted and otherwise moved in a 3D way I think you’ll find yourself manually keyframing. Anyway. You need to animate the position of the tennis ball by keyframing it’s POSITION property so that it matches the glass movement. Unless I misunderstand you really don’t need to do anything to the glass layer, it’s all about animating the tennis ball to match the glass movement, whether that is through the tracker or you manually doing it frame by frame.
To sell the illusion you may have to play with the blending mode of the tennis ball as well as lighting and distortion if it’s to look like it’s IN the glass.
Alex
Lightdrop Video Production, Editing & Design -
You can’t parent a layer to a mask, you can only parent layers to other layers. A layer with a parent will follow its parent’s transformations (position, rotation, scale). If your glass layer is video footage (it sounds like it is) then the layer’s position/rotation/scale properties are not animated as the glass moves and the tennis ball will not move.
You could try using the Motion Tracker to track the position/rotation/scale of the glass, this will be easier if it has some very identifiable characteristics (a logo on the glass?). I would recommend then applying this tracker data to a null object.
You can then parent the tennis ball to the null object, so as the null object follows the transformations of the glass, the ball will follow the null object and you will still be free to animate the tennis ball’s position/scale/rotation to give it some random floating motion (or whatever look you’re trying to simulate).
This all depends on you being able to get a good track on the glass though.
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I was thinking of using the null object to parent, but thought it would be too much work as I would have to keyframe the null object’s movement, then parent the tennis ball. Your suggestion is a good one. I have never used motion tracker, so now is a good excuse to learn.
OMU
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