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pupil-labs / apriltags

Python bindings for the apriltags3 library
https://pupil-apriltags.readthedocs.io/en/latest/index.html
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Questions about tag position #36

Open TON14 opened 3 years ago

TON14 commented 3 years ago

pose_t = [[-0.16225682] [-0.20048863] [ 1.01195728]]

for simplicity x = -0.16225682 y = -0.20048863 z = 1.01195728

  1. what units? Look like meters
  2. x - is it left\right y - is it up\down z - is it distance or forward\backward
  3. Is it relative to the center of the image or relative to the optical center (cx,cy from camera_params)?
dmklee commented 3 years ago
  1. The units are based on whatever you provide for the tag_size argument to Detector.detect. So if you have a 2cm tag and you use tag_size=2 then the units are cm; if you use 0.02 then your units are meters.
  2. x&y are in the plane of the tag, z is moving perpendicular to the plane
  3. it is in the coordinate frame of the camera. I found the cv2 tutorial on pose estimation helpful for understanding how to move from camera coordinate frame to a more interpretable world coordinate frame.