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asked 2013-06-11 05:06:19 -0500

acp gravatar image

updated 2013-06-11 22:35:05 -0500

Dear all.

Just wondering whether it might be possible to clean the last transformation from a "New User N".

In other words, when I stand in front of the Xtion Pro live I get the transformation from "/openni_depth_frame" to "/right_hip_1" then I move away from the sensor, but it keeps giving me the last transformation. And the function

listener.waitForTransformationform("/openni_depth_frame","/right_hip_1",right_hip_point_1.header.stamp, ros::Duration(3))

keeps giving me true and I cant use other transformations from other New Users.

In advance I appreciate your help.

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answered 2013-06-11 20:42:52 -0500

I am not using Xtion Pro, but for kinect, but it is the same openni_tracker.

I would say that in fact you make two mistakes :

  • as soon as you live the frame, the transformation "/openni_depth_frame" to "/right_hip_1" disappears in almost no time (less than two seconds). However, if you are using RVIZ, you have a parameter you can change : In RVIZ, in the pannel Displays, under TF you have "Frame Timeout". Try putting this to 0, and you will not see the transforms anymore, as soon as you left the frame.
  • The second mistake concerns your use of listener.waitForTransform : as you can see on this tutorial, the third argument is the moment at which you want to know the transform was. Here, it seems that you always ask for a transform in the past, at the last moment you found the right hip. Thus leading to a seemingly always existing transform. Try to replace right_hip_point_1.header.stamp by ros::Time::now(), and you should not have it anymore.

The combination of the two thus lead you to think the transform was still here after you left the frame, whereas in fact it is not :-)

Let me know,

Bests regards,


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Hi Step, thanks for your answer, I have tried to change the parameter 'Frame Timeout' under 'TF' to zero, but for some reason rviz does not allow me, it always end up with 1.

acp gravatar image acp  ( 2013-06-11 22:25:42 -0500 )edit

Ok, I always put 1 also :-S Sorry for the mistake ^^ By the way, is it "normal" now ? If yes, please mark my answer as correct. If not, let me know the remaining problems (edit your question with a [EDIT] tag, so I can also modify my answer) Bests

Stephane.M gravatar image Stephane.M  ( 2013-06-11 22:28:00 -0500 )edit

Hi Steph, well, some how, I can not use the edit tag. But it seems to be that it is working now.

acp gravatar image acp  ( 2013-06-11 22:49:09 -0500 )edit

I have a question, what is the best to track, the hip, shoulder etc....thanx :)

acp gravatar image acp  ( 2013-06-12 01:43:55 -0500 )edit

If my answer solved the problem, mark it as the correct answer please. Then, for another question, open a new question, never ask a question as an answer or comments ;-)

Stephane.M gravatar image Stephane.M  ( 2013-06-12 21:41:10 -0500 )edit

I think I have mark it as correct question, if not where can i do that? :)

acp gravatar image acp  ( 2013-06-13 06:11:22 -0500 )edit

Near my post, on the left, there are two arrows, with a "1" between. And just under a "v" inside a grey circle, you click there to mark my answer as correct :-)

Stephane.M gravatar image Stephane.M  ( 2013-06-13 06:20:39 -0500 )edit

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Asked: 2013-06-11 05:06:19 -0500

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Last updated: Jun 11 '13

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