This reporter returns a selected property of a detected tag from the latest camera analysis.
The tag index identifies the result within the current list of detected tags.
Available Attributes
| Attribute | Returned information |
| ID | Unique numerical ID encoded in the AprilTag |
| X Position | Horizontal pixel offset of the tag centre from the camera-frame centre |
| Y Position | Vertical pixel offset of the tag centre from the camera-frame centre |
| Width | Width of the detected bounding box in pixels |
| Height | Height of the detected bounding box in pixels |
| Rotation (deg) | Two-dimensional rotation of the marker |
| Confidence | Reliability value of the detection |
| 3D Position X (cm) | Horizontal position relative to the camera centre |
| 3D Position Y (cm) | Vertical position relative to the camera centre |
| 3D Position Z (cm) | Forward distance from the camera |
| Yaw (deg) | Left or right rotational orientation |
| Pitch (deg) | Upward or downward tilt |
| Roll (deg) | Sideways tilt |
Rotation Direction
For the two-dimensional Rotation attribute:
- Positive values indicate anti-clockwise rotation.
- Negative values indicate clockwise rotation.
Understanding X, Y and Z
- X Position: Indicates whether the tag is to the left or right in the image.
- Y Position: Indicates whether the tag is above or below the image centre.
- 3D Position Z: Represents the approximate distance between the camera and tag.
The values update every time the camera image is analysed. A moving robot will therefore receive changing position and distance values as it approaches or passes the tag.
Accurate 3D position and pose values depend on the correct tag size and camera calibration used by the extension.