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Signifiance of fixed_frame parameter in lookupTransform function

asked 2021-07-14 08:53:02 -0500

updated 2021-07-15 07:40:55 -0500

I was going through the implementation of the lookupTransform function defined inside the base_local_planner::getGoalPose() function.

What is the significance of the fixed_frame parameter in tf2_ros::Buffer::lookupTransform (target_frame, target_time, source_frame, source_time, fixed_frame, timeout) function ?

The documentation mentions the following - Get the transform between two frames by frame ID assuming fixed frame.

What's preventing us to always go for the other implementation of the lookupTransform function - tf2_ros::Buffer::lookupTransform (target_frame, source_frame, time, timeout) ?

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answered 2021-07-15 11:29:24 -0500

tfoote gravatar image

If you use the advanced API you're transporting the data in time. As such you need to tell tf which coordinate frame it is considered fixed during the change in time.

There's tutorials on this in the main tf2 tutorials for both C++ and Python

You can also read about it in the 2013 paper: http://wiki.ros.org/Papers/TePRA2013_...

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Asked: 2021-07-14 08:53:02 -0500

Seen: 53 times

Last updated: Jul 15 '21