How do I reconstruct a TF tree from a rosbag?

If I play a rosbag in a terminal and then run

tree = rostf;

I can view the TF tree and access the transforms between frames. What I would like to do is extract the TF tree from the rosbag directly. This should be possible as I have direct access to the '/tf' topic.

A possible acceptable hack would be a way to execute 'rosbag play filename.bag' from the MATLAB script directly.

Ideally, there would be functionality that could work something like the following:

bag = rosbag(filepath);
selectOptions = {'Topic', '/tf'};
bagselect = select(bag, selectOptions{:});
tf = getTransform(bagselect, 'map', 'odom', timestep);

[Kyle Stanhouse]

It sounds like you might have been trying to do the same thing I was - use the Matlab ROS functions to access rosbag files and apply tf's to certain entities, possibly using 'waitforTransform()'? Did you ever find a resolution?

Answer 1

[Josh Chen]

Hello David,

Yes! You may consider to use the getTransform function in BagSelection Object or rosbagreader Object to get the transformation between two frames in a specific rosbag.

This example shows how to access the transformation from a bag file.

Hope that helps,

Thanks,

Josh