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Hi,

I have been using the individualMarkers node from the ar_track_alvar package successfully. With the individualMarkersNoKinect however, the detected markers are about 5 cm 'below' the right location. Apparently this depth data based improvement is important: if I comment out the

int ret = PlaneFitPoseImprovement(i, m->ros_corners_3D, selected_points, cloud, m->pose);

line in the individualMarkers code, I get a similarly large error.

Is that really the best accuracy you can get without using the depth data?

I am using a close range primesense camera with markers not more than 1 meter away from the camera. The marker size is 7 cm. When using the individualMarkersNoKinect node, I use the following topics: /camera/rgb/image_raw
/camera/rgb/camera_info

Thanks for any feedback,

Bert


Originally posted by bwillaert on ROS Answers with karma: 11 on 2014-03-06

Post score: 1


Original comments

Comment by bwillaert on 2014-03-11:
In the meantime, I did a calibration of the rgd camera (using http://wiki.ros.org/camera_calibration) and that improved the 2d based tracking accuracy. The errors are now < 2 cm in the direction from the camera to the marker location. Depending on the camera quality and the calibration quality, I assume now that's the best possible...

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1 Answer 1

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This seems odd. If the position of the tag is being estimated as "behind" where the tag really is, it usually means that the measurement of the size of tag is incorrect, leading it to think it is a different distance away. The measurement should be done from side to side (not corner to corner) of the black edges of the tag.


Originally posted by sniekum with karma: 101 on 2014-04-30

This answer was ACCEPTED on the original site

Post score: 1


Original comments

Comment by bit-pirate on 2015-12-08:
Is the assumption correct, that one is supposed to measure the outside edges (e.g. furthest left black edge to furthest right black edge)?

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