tf Listener for OpenNI Tracker [Solved]

Question

Hello all, I want get joint coordinates of skeleton. I understand that I can get this information using tf listener as mentioned here. http://wiki.ros.org/tf/Tutorials/Writing%20a%20tf%20listener%20%28C%2B%2B%29

But I have problem in understanding how to mention each joint(from pi pose) in this section of code. while (node.ok()) { tf::StampedTransform transform; try{ listener.lookupTransform("/turtle2", "/turtle1", ros::Time(0), transform); }

is it possible for any one to guide me or provide an example code so that I can get all the joint coordinates.

EDIT

int main(int argc, char** argv) { ros::init(argc, argv, "my_tf_listener");

ros::NodeHandle node;

ros::service::waitForService("spawn");
ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("spawn");
turtlesim::Spawn srv;
add_turtle.call(srv);

tf::TransformListener listener;

ros::Rate rate(1.0);
while (node.ok())
{
    tf::StampedTransform transform;
    try
    {
        listener.lookupTransform("/head", "/neck","/torso",
                                    "/left_shoulder","/left_elbow","/left_hand",
                                        "/right_shoulder","/right_elbow","/right_hand",
                                            "/left_hip","/left_knee","/left_foot",
                                                "/right_hip","/right_knee","/right_foot",
                                                        ros::Time(0), transform);

    }
        catch (tf::TransformException &ex) 
    {
    ROS_ERROR("%s",ex.what());
    ros::Duration(1.0).sleep();
    continue;
}

rate.sleep();
}
return 0;

};

I'm trying to do this, but I'm getting error during compilation.

error: no matching function for call to ‘tf::TransformListener::lookupTransform(const char [6], const char [6], const char [7], const char [15], const char [12], const char [11], const char [16], const char [13], const char [12], const char [10], const char [11], const char [11], const char [11], const char [12], const char [12], ros::Time, tf::StampedTransform&)’ ros::Time(0), transform); ^

Thanks, Regards, Prasanna

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Originally posted by PKumars on ROS Answers with karma: 92 on 2016-03-28

Post score: 1

Answer 1

The listener only looks up the transformation between two frames. What do you expect your call to provide? You only pass a single transformation, but a huge list of frames. If you want multiple transformations, you have to call lookupTransform several times, each time with a pair of frame-names.

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Originally posted by NEngelhard with karma: 3519 on 2016-03-28

This answer was ACCEPTED on the original site

Post score: 2

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Original comments

Comment by PKumars on 2016-03-28:
OK. Thanks a lot for your reply. But if I put "/head" as one transform then what should be the second transform?

Comment by PKumars on 2016-03-28:
Sorry for the confusion. I want to get coordinates with respect to kinect frame. so what should I use as a second transform to get position with respect to kinect frame origin? Thanks..

Comment by NEngelhard on 2016-03-28:
I think you should reread the tutorials as you are mixing things. "/head" is no transformation but a frame. A transformation consist of the information of how you transform poses that are given in one frame into another frame.

Comment by PKumars on 2016-03-30:
Thanks for your guidance. I solved the problem. I'm posting it as an Answer. hope you have no objection.