About Apriltags

AprilTags are a common type of visual fiducial marker. Visual fiducial markers are artificial landmarks added to a scene to allow “localization” (finding your current position) via images. In simpler terms, tags mark known points of reference that you can use to find your current location. They are similar to QR codes in which they encode information, however, they hold only a single number. By placing AprilTags in known locations around the field and detecting them using PhotonVision, you can easily get full field localization / pose estimation. Alternatively, you can use AprilTags the same way you used retroreflective tape, simply using them to turn to goal without any pose estimation.

A more technical explanation can be found in the WPILib documentation.

Note

You can get FIRST’s official PDF of the targets used in 2024 here.