Re: Map update - node statistics, aging and delete

Posted by matlabbe on
URL: http://official-rtab-map-forum.206.s1.nabble.com/Map-update-node-statistics-aging-and-delete-tp10663p10670.html

Hi akunin,

I have thought about it too, but I didn't have time to try it to make a working example. Similarly to your idea, I was thinking about making a semi-continuous mapping approach by recording data while the robot is in localization mode, then detect, by some re-localization statistics, the areas the robot didn't re-localize as often as before. An offline tool could select areas with low re-localization rate and do an "append" with nodes recorded during the localization session around that area, then finally discard the old nodes of that area.

Ideally, we may want to update the map before the robot cannot re-localize anymore in an area. Using the number of matches/inliers could help to identify where the re-localization recall would slowly decrease over time. To do so, we would need to record statistics over time for the nodes in the map: how many times we localized on? How many inliers/matches we had when localizing on? The assumption is that if the environment slowly changes over time, we would see inliers/matches over a specific node decreasing over time. For fast drastic changes, the robot would not re-localize, so a statistics about how long the robot has been close to a node in the map without re-localizing could be another statistic. However, if the robot is mislocalized, that could affect wrongly that statistic. Note also that for some nodes, we may never relocalize on (e.g., heavily textureless/white wall areas), so may not need to be replaced.

cheers,
Mathieu