how is external odometry added to graph?

Posted by Geert Folkertsma on
URL: http://official-rtab-map-forum.206.s1.nabble.com/how-is-external-odometry-added-to-graph-tp10883.html

I'm a bit lost after going through the codebase, so I hope someone here can give me a pointer where to look.

I'm trying to find out how the external odometry (e.g. from robot_localization) is added to the graph. I'm especially interested in how the covariance of the odometry message is used; and how multiple odometry messages between nodes/signatures(right?) are combined into a constraint.

Can someone point me to some places in the code where the odometry comes in (ros subscriber), and through which path it gets added to the graph? I've found some bits and pieces, but the complete path is not clear to me.

In my use case, rtabmap also receives laserscan data (which it may use for proximity matches or not), and gps measurements (which it may use with ignorePriors=false). I want to better understand how increasing covariance of the robot_localization's EKF (no corrections, after all) ends up in the graph.