Transform timestamped messages recorded in a bag file using tf messages

asked 2017-04-30 01:45:09 -0600

nbro gravatar image

updated 2017-04-30 01:54:26 -0600

I have a .bag which contains recorded messages on topics /topic1 and /topic2. The messages have /world as frame. Both of the messages associated with these topics are stamped, i.e. they have a header.

The same .bag file also contains recorded messages on the topic /tf (of type tf2_msgs/TFMessage). These transform messages have the frame_id set to /world and the child_frame_id set to the local frames associated with the IMUs from which the messages are being sent over respectively topic /topic1 and /topic2.

Now, I need the messages sent over the /topic1 and /topic2 to be converted to their corresponding local frame (i.e the child frame) from the fixed frame /world. Since both the /tf messages and the messages of the topics /topic1 and /topic2 are stamped, I thought we could do this without much trouble, but I'm not sure since I'm very new to ROS.

I've looked around for various solutions, but I didn't find an exact solution for my problem, maybe because I didn't recognize it as such, given my limited knowledge of ROS, as I said.

I would appreciate a step by step description of the approach and, if you don't want to write a full solution with code, at least point me to the similar examples. Please, do not suggest me to read the tutorials of /tf, I've partially done it, and it didn't help much.

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