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ar_pose : interprete output of 'ar_pose_marker' && transform

asked 2013-11-06 12:12:06 -0500

pr2rp gravatar image


I want to track a object that is moving inside a room and color the pixel in the cam-image, where the object has moved to. Instead of detect colors etc. I want to do this with markers from ar_pose.

My setup is a simple web_cam and one printed marker. I can start tracking and I do get values on the topic "ar_pose_marker". My problem is that I do not understand what the values "ar_pose_marker" is publishing to me. Yes, I did read that "The current pose of the marker relative to the camera." My interpretation is that the cam is located at (0,0.0) and the values are the offset to that origin (in world coordinates). Is that correct?

One example: Lets say my setup is running with a 640x480px image. When i move the marker to the most left: {ar_pose_marker}.x = -1.16 The the rightmost place {ar_pose_marker}.x = -0.75

This values change when i increase/decrease the distance: marker<->camera. Whay?

  • What does the values ^^ tell me?
  • How do I transform a detected marker position to a specific pixel position in the cam-image?

Thanks for any hints

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answered 2016-04-14 09:40:37 -0500

updated 2016-04-14 09:40:48 -0500

Maybe the axis are not aligned, I'm just guessing. I'm working now on the same problem and I noticed the same as you. If you got an answer to this problem (since you worked on it two years ago) please answer me.

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Asked: 2013-11-06 12:12:06 -0500

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Last updated: Apr 14 '16