For context, AprilTags are a fiducial system that can be used both for IDs (similar to a QR code) and determining relative positions (i.e., they were specifically designed to maintain accuracy with this task).
Ideal specifications:
- something close to a one-click order
- adhesive backing, which is removable (OK if it takes a bit of effort)
- three sizes (i.e., “small, medium, large”) (can also base it loosely off of Hiwonder’s defaults)
- rigid
- chemical compatibility becomes a consideration. I think I had looked into this a fair bit, but I’m having trouble finding where I put those notes. Maybe better if this is done through a lamination rather than trying to get it printed directly on
In terms of choosing a tag family:
For the vast majority of applications, the tagStandard41h12 family will be the correct choice. You can find the images for the tags in the apriltag-imgs repo. Scale up the images in your favorite editor and print them out.
Some heuristics for when to choose other tag families:
- If you need more tags, use tagStandard52h13
- If you need to maximize the use of space on a small circular object, use tagCircle49h12 (or tagCircle21h7).
- If you want to make a recursive tag use tagCustom48h12.
- If you want compatibility with the ArUcO detector use tag36h11
If none of these fit your needs, generate your own custom tag family here.
It seems apriltag-imgs/tagStandard41h12 at master · AprilRobotics/apriltag-imgs · GitHub has ~1115 images (2 at the start were other files). However, it wouldn’t be so bad to print other tag sets in that repo. For example, apriltag-imgs/tagCircle49h12 at master · AprilRobotics/apriltag-imgs · GitHub and apriltag-imgs/tagCustom48h12 at master · AprilRobotics/apriltag-imgs · GitHub (note: these are on the order of ~50000 files, but I could only print the first 1000 for example).
In terms of scaling to different sizes, the image repository also says:
Alternately, you can use the supplied native Python 3 script tag_to_svg.py to create a SVG (Scalable Vector Graphics) Version of a tag. For example:
python3 tag_to_svg.py tagStandard52h13/tag52_13_00007.png tag52_13_00007.svg --size=20mm
Some vendors based on Google Search
- April Tags - VR & AR Markers - Robotics Fiducial System
- This has a choice between sticker and magnetic backing, e.g., 16-bit AprilTags (3"x3") | Magnet for Auto-Detection | 30 Pack (3"x3")
- AprilTag Targets | High-Accuracy Calibration Boards
Likewise, in terms of AprilTag software, there is the official one which requires some manual installation:
Or a non-official, but pip-installable version: pupil-apriltags 1.0.4.post9.dev1+gfff8536 (which could be a reasonable version)
It would be awesome to have a pip-installable version attached with the main repo, though.
EDIT: GitHub - duckietown/lib-dt-apriltags: Python bindings to the Apriltags library provides Python bindings for the official repo (and is even mentioned in the official repo README), but it’s pinned to a 2021 version of apriltags and hasn’t been updated since 2023.