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Over the course of a shot, the plane that is being tracked can change substantially, especially due to lighting changes where the plane brightens up due to its alignment to a light source, due to changes in the image being tracked (ie it is not fully planar), due to resolution changes, or other shot-dependent effects. Those changes can cause tracking to be lost or to drift off target systematically.
When this occurs, back up to a recent time when tracking was doing well, and double-click the main tracker rectangle. This will set new corner keys at exactly the tracked locations, and this optical pattern will be used for following frames. You can do this repeatedly over the course of a shot.
Tricky Tip : this kind of re-keying to accommodate lighting changes is the done automatically for regular trackers by the Key Every setting—and you can set up a Key Every setting for a planar tracker . Since this setting is not visible from the Planar tracking panel, it is easy to forget you have set it!
Be careful that you don't unwittingly add a key when a small object moves in front.
Warning : You can't delete an auto-key, because it is instantly re-set. You must change the auto-key value, add a new key somewhat before the bad auto-key, so that the next auto-key is pushed later in the sequence..
If you need to make changes in the original main key frame, you'll need to re-set the additional keys, either by deleting them en masse in the graph editor, say, or individually as you reach them when re-tracking. To remove the existing key, shift-right- click the main tracker rectangle (as you can with the search rectangle). To delete all keys except that on the main frame, shift-control-right-click.
When you add additional keys by repositioning the corners (not by double- clicking), the corner locations will be limited so that the 3-D aspect and field of view exactly match those of the main frame, except that the field of view will be alterable for zooming 3-D planars.
©2023 Boris FX, Inc. — UNOFFICIAL — Converted from original PDF.