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Motion tracking tips
Sorry in advance if this is the wrong forum but I’m in need of advice!
I have been asked to help out on a film soon to be shot. One of the scenes requires lots of photographs pinned to a wall. The camera will slowly zoom into one of these photos where it will be replaced by some moving footage as the camera pans in.
My question is, how can I make this easy for myself? I think corner-pinning in After Effects is the way to go, tracking points on the corners of the photograph, but how should I prep this photo? Should I draw big dots near each of the corners of an “empty” photo for the Tracker Controls to accurately grab hold of or is there a better technique?
Many thanks. Mark.
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4 Replies
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The best (I’ve heard) marker is a chevron, creating a point where the software can focus.
Chevron: a V or an L.
Steve
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If there is enough contrast between the frame and the greenscreen in the picture area, then you don’t need trackers. The corners themselves usually do a nice track. Then when you key the green you don’t have to do a separate matte to get rid of the trackers. Will the camera be pushing forward toward the pics or will it be a zoom (just focal length change)? If it pushes in, then you will probably get a nice moving sheen off the glass in front of the picture (or greenscreen in this case) you will want to preserve this sheen and lay it back over your comped in picture so it looks truly integrated behind the glass. If you paint tracking markers, then the dots get in the way and would have to be painted out. I talk to online guys who get pissed when we put tracking markers in a shot that already has trackable corners because it’s only more work for them to remove them.
Chris Smith
https://www.sugarfilmproduction.com -
What do you mean a seperate matte? Once you key the green and lets say you have ur red tracker markers , do you duplicate the layer and track the bottom one with the markers on it and the top one showing has the markers painted out?
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Well the only reason you have a green screen is for the very edges. so the picture will have edges that conform to the frame. If the trackers are just inside the edges, use the same corner pin info on a garbage matte layer that is a touch smaller than your picture layer and set the matte comp to subtract from the keyers alpha. Because the keyer will still show the trackers as positive alpha. You need to add a matte over those to make them transparent. Since you already did a 4 corner track, you might as well use that data to move your garbage matte.
But as I said, I don’t think you’ll need tracking markers, And if you did, you would probably track by luminance so making them red won’t help unless you plan on tracking by hue.
Chris Smith
https://www.sugarfilmproduction.com
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