ros2 / ros2/geometry2

Puzzle on how to rotate convariance

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Dominant language
C++
Stars
153
Forks
256
Avg merge
3d 23h
Merged PRs (30d)
14

Description

The following code is how this repository rotate covariance:
https://github.com/ros2/geometry2/blob/d1dc38b8a0e706fbd67a800a241fee950fce39f4/tf2_geometry_msgs/src/tf2_geometry_msgs/tf2_geometry_msgs.py#L101-L104

This is how mrpt rotate covariance:
https://github.com/MRPT/mrpt/blob/4af6ea558bf75af9bc9798abfc3745fe7ce39c66/libs/poses/src/CPose3DPDF.cpp#L134-L158

Obviously different. It seems euler angles cannot be rorated via left-multipling a rotation matrix. Therefore, transforming a covariance matrix of euler angles is not the same as transforming translation's:

$$
Cov(RX)=R\cdot Cov(X)\cdot R^T
$$

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Compare the linked tf2_geometry_msgs.py lines 101-104 with MRPT's CPose3DPDF.cpp lines 134-158, focusing on how covariance for Euler angles is transformed. Establish which behavior is correct for this repository, then capture the decision in the issue or an appropriate change with a clear validation case.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, python
Domain
robotics
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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