Accuracy requirement of odometry input for rtabmap when mapping

Posted by cactus on
URL: http://official-rtab-map-forum.206.s1.nabble.com/Accuracy-requirement-of-odometry-input-for-rtabmap-when-mapping-tp8199.html

Hello! I'm pretty new to rtabmap and I'm slightly confused by a few things. The first question should just be a clarification, while the second question is the "meat" of this post and requires the first question.

1. There's the distinction between mapping mode and localization mode. The mapping mode is still performs localization with mapping, but only on loop closure, correct? The localization mode, on the other hand, assumes a good map and performs localization all the time. This implies that when in mapping mode, rtabmap only publishes map -> odom on loop closure and at no other time?

2. If mapping mode is doing localization _only during loop closure_, that means if you drive the robot in a straight line for a long time, the quality of the map generated will depend heavily on the quality of the input odometry? In my particular example, I have wheel odometry and IMU (within a realsense D435i) on a differential drive robot (two wheels). I observed pretty heavy drift in wheel odometry and the IMU appears to suffer from a large amount of drift. As a result, I don't think the odometry can be accurate for more than 5 seconds or so. Using this number, does it imply that I need to structure my driving in a way that loop closure can be performed every 5 seconds when building the map initially?

Thanks!