Producing Moving Objects

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‌Producing Moving Objects

Similar to producing a 3-D planar tracker, the AprilTag Detector can also be told to produce SynthEyes moving objects via the Moving Object mode. You can parent meshes to the moving object, export it, etc.

You’ll need to specify the Tag Size, ie the green line in the graphic in the planar tracking section. You’ll also need to have previously determined or estimated the camera field of view, and set it up into the camera’s seed or solved FOV track.

In order to produce decent data, especially for orientation coming up out of the tag, the tag will have to be fairly large in the image. Below is a screen capture from a 4K shot (aka “two-man bobsled”) with two 16H5 tags on a phone. There’s a reasonable degree of stability despite the extreme out-of-plane nature of the shot and ease of tracking. In this shot, when a finger occludes the bottom tag, it is lost, but it is possible to continue tracking that particular tag using a planar tracker.

Note : the 3-D calculations for SynthEyes’s planar trackers and AprilTags are a bit different, and AprilTags is not enforcing shared FOV and possibly aspect constraints. As a result AprilTags may produce output on frames that SynthEyes does not, especially on low-perspective frames.

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