A Sword

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Here we want to track a sword in 3D, from only a single camera. The sword itself needs to be a special prop, with easily trackable features not only at the tip and hilt, but at two intermediate locations as well. For example, a rigid rod with several table-tennis or foam balls impaled upon it. You'll need to measure the distance of each ball along the rod.

This effect can be solved with a single hybrid 2D GeoH object with supervised trackers on each ball, configured with appropriate locks to the measured distances. Unlock all the axes except roll—the sword is rotationally symmetric so there's nothing to be gained there (unless you add another ball somewhere off-axis on the hilt).

There can be two similar solutions, one with tip closest, the other with handle closest. You should be able to tilt the table to the right solution by prepositioning the rig before enabling solving.

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