[Request for Input] Potential Existing SLAM Toolbox Serialized File Invalidation

ROS ROS General
9

Awesome: As a final resolution this is what we’re doing

  • Maintaining separate unfixed branches for all released distributions
  • Adding to readme a link to this discussion and the resolution
  • Merging and releasing updates of all other distributions for this patch

The new readme section reads

As of 03/23/2021, the contents of the serialized files has changed. For all new users after this date, this regard this section it does not impact you.

If you have previously existing serialized files (e.g. not pgm maps, but .posegraph serialized slam sessions), after this date, you may need to take some action to maintain current features. Unfortunately, an ABI breaking change was required to be made in order to fix a very large bug affecting any 360 or non-axially-mounted LIDAR system.

This Discourse post highlights the issues. The frame storing the scan data for the optimizer was incorrect leading to explosions or flipping of maps for 360 and non-axially-aligned robots when using conservative loss functions. This change permanently fixes this issue, however it changes the frame of reference that this data is stored and serialized in. If your system as a non-360 lidar and it is mounted with its frame aligned with the robot base frame, you're unlikely to notice a problem and can disregard this statement. For all others noticing issues, you have the following options:

    Use the <distro>-devel-unfixed branch rather than <distro>-devel, which contains the unfixed version of this distribution's release which will be maintained in parallel to the main branches to have an option to continue with your working solution
    Convert your serialized files into the new reference frame with an offline utility
    Take the raw data and rerun the SLAM sessions to get a new serialized file with the right content

More of the conversation can be seen on tickets #198 and #281. I apologize for the inconvenience, however this solves a very large bug that was impacting a large number of users. I've worked hard to make sure there's a viable path forward for everyone.