# AprilRobotics/apriltag

AprilTag is a visual fiducial system popular for robotics research.

Repository: https://github.com/AprilRobotics/apriltag
Canonical: https://ross.abutalabs.com/products/apriltag
Homepage: https://april.eecs.umich.edu/software/apriltag
Language: C
License: NOASSERTION
License Family: other
Topics: robotics
Last push: 2026-08-07T17:19:29+00:00

## Health v2 (maintenance only)
Score: 71/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 96, release rhythm 21, longevity 100
- inputs: {"age_days": 2906, "days_push": 26, "days_rel": 369, "gap_med": 97.0, "n_releases_24m": 3}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2480, forks 672 (observed 2026-08-28T04:06:55.259616+00:00)

## What it is
AprilTag is a small C library implementing a visual fiducial (marker) detection system, computing the precise 3D position, orientation, and identity of printed tags relative to a camera. It has minimal dependencies, is portable to embedded devices, and includes bindings for Python, Matlab, and Julia.

## Use cases
- detect fiducial markers for robot localization
- estimate camera pose from printed tags
- calibrate a camera using fiducial targets
- add marker-based tracking to augmented reality apps
- detect AprilTags in real time on embedded hardware
- identify tags and their 3D position from images

## When to choose
- you need robust, fast detection of printed 2D fiducial markers in C or Python
- you need precise 3D pose of markers for robotics or AR
- you need a dependency-free library portable to embedded devices
- you want a well-established, research-backed fiducial system

## When to avoid
- you need to encode large data payloads (use QR codes instead)
- you need a pure high-level-language solution with no C compilation
- your platform is not Linux/POSIX-like and you cannot port the build

## Facets
- artifact type: library
- maturity: stable
- function: computer-vision, image-processing, sdk
- domain: robotics, computer-vision, autonomous-vehicles
- platform: cross-platform, embedded, python, cpp, c
- tags: fiducial-detection, apriltag, pose-estimation, camera-calibration, augmented-reality, marker-detection, augmented reality, linux

## Member repositories
- AprilRobotics/apriltag (main) score 71

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:55.259616+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:28:15.224173+00:00, confidence not recorded.
  - readme: https://github.com/AprilRobotics/apriltag (fetched 2026-08-28T04:06:55.259616+00:00, sha 9fae30da39d5)
  - homepage: https://april.eecs.umich.edu/software/apriltag (fetched 2026-08-29T10:10:06.618268+00:00, sha cc2e1c4090bf)
- Data as of 2026-08-30T08:39:29.467469+00:00.