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Openni_tracker subscriber and more

asked 2014-06-11 14:03:02 -0500

morenot gravatar image

Hi I am really new with ROS, what I want to do is track the skeleton using openni_tracker with groovy which is already working but I need to get the data from the joints (position) and I can see it with rostopic echo /tf, but my I have some questions.
1.- How can I actually interpret the output values?
2.- The openni_tracker is path is "opt/ros/groovy/stacks/openni_tracker" and I do not know how to write a subscriber to the transforms, I saw the tutorial but did not help much
3.- Is there any way I can put the openni tracker inside my own workspace? because I tried several things but it kept thrwoing errors during the rosmake

Any help will be much appreciated

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answered 2014-06-11 17:15:55 -0500

kramer gravatar image

I just recently got openni_tracker working but don't have the hardware in front of me right now, making it difficult to give specifics. Assuming it is actually working for you, it sounds to me like you just need to become more familiar with TF. (I say that because, rather than 'rostopic echo /tf', you probably want to try using 'rosrun tf tf_echo <source_frame> <target_frame>'.)

What would likely be most instructive is to run RViz and add the TF display, setting the 'Global Settings -> Fixed Frame' to the appropriate frame (again, sorry, I don't have it in front of me and can't recall the default frame name). If it's working, you'll be able to see a 'skeleton' of connected 3-axis display objects, where each axis object is a joint being tracked.

In terms of actual code, you likely want to spend more time on the Writing a tf listener tutorial. The various skeleton joint frames will move relative the sensor's fixed frame and can be accessed using a transform listener's lookupTransform method.

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Asked: 2014-06-11 14:03:02 -0500

Seen: 301 times

Last updated: Jun 11 '14