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Overall Distance Locks
When a shot contains little perspective, virtually all the error will be in depth, ie the distance from the camera to the rest of the scene (or from an object to its camera). Even the tiniest amount of jitter in the tracking data can produce a large amount of jitter in the depth: this is not a program problem, but a reflection of the poor quality of the available information.
SynthEyes allows you to set up a soft lock (only!) on this depth value, the distance from the camera to origin, or object to camera, using the Solver Locking panel. The Constrain checkbox must be on for these constraints to be effective!
You can animate this desired distance based on the measured distances from an original track, using the Get 1f button for the Overall Distance, typically on a small number of frames.
In this fashion, you can force the depth value to have a very smooth trajectory, while allowing a dynamic performance in the other axes. This often corresponds relatively well to what happens on the set.
You can configure and check this constraint using the Distance channels of the Camera: the Seed Path Distance value shows the value being constrained to, the Solved Path value shows the actual value (whether or not a distance constraint is active), and the Solved Velocity Distance value shows the velocity of the actual value. The velocity value is helpful to determining whether or not the constraint has been fully effective or not; if the velocity is not very smooth to match the commanded value, you should increase the weight of the distance constraint on the solver locking panel. Do that on the first frame, to avoid placing weight keys in the middle of the shot (unless that is what you want).
Note that you must set up a coordinate system on the camera or object in order to productively use these constraints, so that the origin is not changing on each successive solving run. And depending on where the camera or object origin falls, the distance curve may be simple and slowly changing, or if the origin is too close to the camera or object the motion may be too dynamic and difficult to work with.
While in theory an overall distance lock can be used to set the overall size of the scene (with the Constrain checkbox off), that is not currently supported. You must have
other constraints to set the scene size, and you should makes sure those constraints do not conflict with your overall distance constraints.
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