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expression to make something appear coplanar
I am struggling with trying to come up with a simple way to make a layer move in relation with another layer as though it is coplanar. I have a simple 3D comp with a mortise frame and a video layer. I want to start out viewing the video and zoom out to reveal the mortise and then zoom out further to reveal other objects. My problem is with the video layer and the mortise. They need to appear coplanar but cannot be because I need to see most of the video layer, necessitating it be back in z space(I don’t want to just see pixels of the video!). since the camera move is not only zooming out from z (but also a pedestal move too) the parallax between the two layers is breaking the illusion. Is there an expression I can feed the video layer to amplify the camera move based on its distance from the motrise? Or am I way over thinking this…
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5 Replies
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When you say ‘mortise’ do you mean ‘frame’ or is this actually a much more complicated apparatus? Is this layer in front of your video layer or behind it currently?
You should be able to
A) move both layers close enough that they appear to be coplanar (parent one to the other and set its z position to .1 or another small value)
or
B) place whichever layer is supposed to be ‘on top’ above the other layer in the timeline and actually make them coplanar… the higher layer in the layer stack will be rendered on top of the other.
Option B can complicate things especially when rotating to view the other side of the apparatus.
Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA -
Darby,
Thanks for the reply. I am probably not explaining myself very well. The mortise frame is a logo with a hole in the middle. The video is actually a piece of 720p footage. By way of analogy say a camera starts out on the porthole of a ship, you don’t see the porthole frame but what is inside the cabin. As the camera moves back in z the porthole is seen then the side of the ship then the ship itself. But what is inside the cabin is not coplanar with the porthole. The practical problem is that i want to see most of the frame of the 720p footage thru the mortise and as the mortise is revealed in the camera move the footage anchor & scale can adjust to in effect remove the parallax of the move (because otherwise the we see the edge of the video frame) thru expressions that sample the angle relationship between the mortise and the camera at each frame, but sadly this is over my head. Clear as mud?
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Try creating a duplicate of your frame, without the hollow center, and making this coplanar with the frame. Then place the footage you want ‘behind’ the frame farther back and use the solid logo as an alpha track matte.
Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA -
That works for keeping the video contained, but it does not solve the relative movement based on parallax. I was thinking there was a more elegant solution. I did just hand track it in.
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[Jim Wilcox] “but it does not solve the relative movement based on parallax. I was thinking there was a more elegant solution.”
You did or did not want parallax?
From your first post I thought that you didn’t want parallax, which would require that the layers actually be coplanar. From your second post it sounded like you wanted parallax, which is why I suggested moving the contents of the frame farther back in space and using a track matte.
One of the solutions should work, the one you use just depends on whether or not you want parallax…
Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA
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