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AprilTags are a visual fiduciary system that you can use to simplify coordinate system setups across multiple shots (and etc). They were developed at the University of Michigan that consists of special monochromatic tag designs and software to efficiently locate and identify them in images. You can read the technical papers there, and hop over to the AprilTag code and tag designs on github. Here’s what one looks like:
One block’s worth of white space around the outside is included in this tag design and is mandatory. This tag hails from the simplest family of tags, 16H5. There are 30 different tags in this group which can be identified uniquely, independent of orientation.
Each one can be identified by number. The tag design incorporates some error detection and correction, so the right tag can be identified, even if one or two bits are read incorrectly. (More on the red ones later.)
The idea is that you can print them out, place them around the set, then have SynthEyes automatically find and identify them. Each tag can be automatically identified and assigned a consistent name in multiple shots from the same set. Little tracker cleanup should be required. Then they can be linked to a reference scene, or 3-D coordinate data exported and imported consistently.
This simplifies applying a common coordinate system to multiple shots from the same real or virtual set. AprilTags are not a replacement for regular tracking, but an assist for solving.
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