Table of Contents

Attribute of Tag index

Description

This reporter retrieves a selected attribute of an AprilTag detected at the specified index.

The available attributes include:

  1. id – A unique integer (e.g., 0, 1, 2…) embedded within the black-and-white grid of the tag
  2. x position – x coordinate of the centre of AprilTag. Coordinates are in stage units in 480 px space ranging from  -240 to 240. 
  3. y position –  y coordinate of the centre of AprilTag. Coordinates are in stage units in 360 px space ranging from  -180 to 180. 
  4. width – It refers to the box width of AprilTag. 
  5. height – It refers to the box height of AprilTag
  6. rotation (deg) – It refers to the number of degrees rotated in any direction. Positive rotation angle value for anti-clockwise rotation and negative angle rotation for clockwise rotation. 
  7. confidence – It refers to the accuracy of the detection and depends on the pose settings and the camera input. 
  8. 3D position x (cm) – x coordinate position in centimeters of the centre of the AprilTag relative to the centre of camera
  9. 3D position y (cm) – y coordinate position in centimeters of the centre of the AprilTag relative to the centre of camera
  10. 3D position z (cm) – z coordinate position in centimeters of the centre of the AprilTag relative to the centre of camera
  11. yaw (deg) – It indicates how far the camera is rotated left/right from facing the tag directly. It represents the rotation about the z-axis.
  12. pitch(deg) – It indicates the vertical tilt of the camera (up/down) relative to the tag. It represents the rotation about the horizontal (X) axis. 
  13. roll(deg)- It indicates the tilt of the camera sideways. It represents the rotation about the forward-pointing (Y) axis. 

For the 2D rotation value:

  • Positive value → Anti-clockwise rotation
  • Negative value → Clockwise rotation

Example

There are no examples documented for this article.