Lidar Labeler Rosbag Loading Error (Ubuntu 20.04): Could not locate the base directory for ros.

Hello everyone,

I try to make use of the Rosbag loading feature (https://de.mathworks.com/help/lidar/ref/lidar.labeler.loading.rosbagsource-class.html). I selected Import > Add Point Cloud and then switched to Rosbag and the loading error appeared.

I have installed the Matlab ROS Toolbox and I have installed ROS noetic

env | grep ROS

ROS_VERSION=1

ROS_PYTHON_VERSION=3

ROS_PACKAGE_PATH=/opt/ros/noetic/share

ROSLISP_PACKAGE_DIRECTORIES=

ROS_ETC_DIR=/opt/ros/noetic/etc/ros

ROS_MASTER_URI=http://localhost:11311

ROS_ROOT=/opt/ros/noetic/share/ros

ROS_DISTRO=noetic

and I have sourced ROS

source /opt/ros/noetic/setup.bash

Why does this loading error still appear?

Thanks in advance

Answer 1

[Cam Salzberger]

Hello Daniel,

Does the error occur if you try to load the rosbag data outside of the Lidar Labeler?

bag = rosbag(filePath);
msgs = readMessages(bag, 1); % Testing with just the first message to start, try more if it works

If the error occurs, my suspicion is that you are seeing a library conflict between the ROS MATLAB libraries and the installed ROS libraries and their dependencies. MATLAB uses ROS Melodic, while you have ROS Noetic installed, so there will be a fair number of different library versions.

Try starting MATLAB without having sourced ROS Noetic and without pointing towards the installed Noetic folders. You may have to double-check your PATH and LD_LIBRARY_PATH environment variables to make sure that no "noetic" folders are still present before starting MATLAB.

It would be helpful to see exact error messages too, at least to make it easier for other users to find this post.

-Cam

[Daniel He]

Hello Cam,

This is really embarassing, but it turns out that I just didn't have my ROS Toolbox installed (even I though I very sure I checked the Box to install the it)

Your answer would have been still helpful, because I figured my mistake out through testing with a similar script from a friend

Thank you for you answer

Daniel