The message type 'velodyne_msgs/msg/VelodyneScan' is invalid

[TZECHIN6]

Please complete the following information:

• Ubuntu 20.04.5 LTS
• ROS2 Galactic
• Downloaded from Official Repository
• ros2 branch
• Docker (attached with docker run script)

Describe the bug I have searched this error message in google... and actually there is no thread talking about this issue :(

The real VLP16 lidar's scan data can be see in Rviz2 in real-time. However, when running ros2 topic hz/echo /velodyne_packets, an error message The message type 'velodyne_msgs/msg/VelodyneScan' is invalid appear. I think this indicated this topic has some issues. For other published topics /scan /velodyne_points both works as usual, e.g. the message is ~10Hz in default.

As I have installed this in another PC with same OS and ROS version, it can echo/hz this topic. And I am also working on autoware project which I think this topic is important, otherwise the pointcloud cannot not be shown/used.

To Reproduce Steps to reproduce the behavior:

1. Run the docker with provided script
2. git clone this repo with ros2 branch
3. rosdep intall && colcon build as usual
4. source the ws
5. ros2 launch velodyne velodyne-all-nodes-VLP16-launch.py

Expected behavior The /velodyne_packets can be echo/hz correctly.

Additional context docker_run.script

#!/bin/bash
# This is the docker run script for cuda/ros2.

CONTAINER_IMAGE="sensors/ros:galactic-desktop-velodyne-v.1.0"

USER_VOLUME="$HOME/ros2_robotaxi-ws/sensors-ws/velodyne_ws:/home/ros/velodyne_ws"
USER_COMMAND=""

echo "CONTAINER_IMAGE: $CONTAINER_IMAGE"
echo "USER_VOLUME:     $USER_VOLUME"
echo "USER_COMMAND:    '$USER_COMMAND'"

# Give docker root user X11 permissions
xhost +si:localuser:root

# Run the container
docker run --name velodyne-devel -dt --restart unless-stopped --gpus all --network host \
    -e DISPLAY=$DISPLAY \
    -v /tmp/.X11-unix/:/tmp/.X11-unix \
    -v $USER_VOLUME \
    $CONTAINER_IMAGE $USER_COMMAND

The ros2 base image is created by myself, over 90% is reference to the official ROS2 document. If it is needed to solve this problem, I will provide it in here.

[JWhitleyWork]

This usually happens when you do not source the workspace in the new terminal before running ros2 topic ....

[TZECHIN6]

Thx @JWhitleyWork . I close the bash terminal and source the workspace again... things just work as normal. I will close this issue. Thanks!