[ar_track_alvar] Master tag doesn't get updated when it's the only one visible

asked 2014-09-10 07:21:51 -0600

Rabe gravatar image

updated 2014-09-11 06:01:26 -0600

Hey guys,

I am running ar_track_alvar on ROS Hydro. I have a bundle file, which represents 2 sides of a box, the master tag being on the front and the other 2 tags being on the right side.

When the camera sees only the side, it extrapolates correctly where the master-tag has to be. But when I turn the box in such a way, that only the master-tag is visible, the transforms for the master-tag don't change. They are still published, but only at the place where they were last extrapolated to be. The Rviz-Markers from the topic /ARmarker_points are at the correct place in the point-cloud, but the transform only changes whenever the other tags are visible.

Here is my marker.xml:

 <?xml version="1.0" encoding="UTF-8" standalone="no" ?>
 17 <multimarker markers="3">
 16     <marker index="14" status="1">
 15         <corner x="-2.5" y="-2.5" z="0" />
 14         <corner x="2.5" y="-2.5" z="0" />
 13         <corner x="2.5" y="2.5" z="0" />
 12         <corner x="-2.5" y="2.5" z="0" />
 11     </marker>
 10     <marker index="10" status="1">
  9         <corner x="4.9" y="-3.1" z="-3.15" />
  8         <corner x="4.9" y="-3.1" z="-8.15" />
  7         <corner x="4.9" y="2.875" z="-8.15" />
  6         <corner x="4.9" y="2.875" z="-3.15" />
  5     </marker>
  4     <marker index="11" status="1">
  3         <corner x="4.9" y="-3.1" z="-10.65" />
  2         <corner x="4.9" y="-3.1" z="-15.65" />
  1         <corner x="4.9" y="2.875" z="-15.65" />
  0         <corner x="4.9" y="2.875" z="-10.65" />
  1     </marker>
  2 </multimarker>

Any ideas why this happens?

Thanks in advance

Edit: No, you are right, start with the basics ;) The transforms are really republished, they do not disappear and I can echo them in the command line. I also checked that the tag is really number 14, if I start the alvar_tracker in single-mode, it get's recognized correctly.

For clarification I made a screenshot: Current position on the left, last extrapolated position on the right

As you can see, ar_track_alvar publishes Rviz-Marker in the correct place, but it publishes the transform and another Rviz-Marker in the wrong position. (The big marker in the right corner is not relevant)

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Are the transforms of the master marker really still published or is it this fade out thing of RViz that it disappears after a while? Did you check that your master marked is really marker no 14 (dumb question, I know)?

BennyRe gravatar image BennyRe  ( 2014-09-11 00:49:12 -0600 )edit

Hello, I am trying to track a bundle with kinect using FindMarkerBundles, but I get errors ERROR InferCorners: "camera_1_rgb_optical_frame" passed to lookupTransform argument target_frame does not exist.". However same parameters work very good with the individualMarkers code. You have any idea?

Amine gravatar image Amine  ( 2014-09-19 06:12:09 -0600 )edit