V4L2 Camera - ROS 2 Foxy

Camera Frame Grabbing with Video4Linux2 (V4L2) for ROS 2 Foxy

Clone

First, we will create a new workspace and clone the code for the v4l2_camera package and some of its dependencies, and will install any further dependencies using rosdep:

# Open new terminal.
$ mkdir -p ~/V4L2_Camera/src && cd ~/V4L2_Camera/src
$ git clone https://github.com/Tinker-Twins/V4L2_Camera.git
# Clone following repositories instead for default functionalities.
# $ git clone --branch foxy https://gitlab.com/boldhearts/ros2_v4l2_camera.git
# $ git clone --branch foxy https://github.com/ros-perception/vision_opencv.git
# $ git clone --branch foxy https://github.com/ros-perception/image_common.git
# $ git clone --branch foxy-devel https://github.com/ros-perception/image_transport_plugins.git
$ cd ..
$ rosdep install --from-paths src -r -y

Build

Now build everything we need and source the new workspace:

$ colcon build --packages-up-to v4l2_camera image_transport_plugins
$ source install/local_setup.bash

Run

And finally you can run the camera node:

$ # Open new terminal.
$ ros2 run v4l2_camera v4l2_camera_node

NOTE: Ignore the following errors/warnings.

[ERROR] [1676909521.403530709] [camera_calibration_parsers]: Unable to open camera calibration file [/home/user/.ros/camera_info/integrated_webcam_hd:_integrate.yaml]
[WARN] [1676909521.403548765] [v4l2_camera]: Camera calibration file /home/user/.ros/camera_info/integrated_webcam_hd:_integrate.yaml not found

View the camera output, for instance by running the RQT image viewer:

$ # Open new terminal.
$ ros2 run rqt_image_view rqt_image_view

When doing so, select the /image/compressed topic rather than the base /image so that the images are streamed much more efficiently (at a higher rate).

Launch

OPTION 1: Launch the camera node and separately view the camera output, for instance by running the RQT image viewer.

$ # Open new terminal.
$ ros2 launch v4l2_camera camera.launch.py
$ # Open new terminal.
$ ros2 run rqt_image_view rqt_image_view

NOTE 1: Ignore the following errors/warnings.

[ERROR] [1676909521.403530709] [camera_calibration_parsers]: Unable to open camera calibration file [/home/user/.ros/camera_info/integrated_webcam_hd:_integrate.yaml]
[WARN] [1676909521.403548765] [v4l2_camera]: Camera calibration file /home/user/.ros/camera_info/integrated_webcam_hd:_integrate.yaml not found

NOTE 2: Select the /image/compressed topic rather than the base /image so that the images are streamed much more efficiently (at a higher rate).

OPTION 2: Launch the camera node and view the camera output.

# Open new terminal.
$ ros2 launch v4l2_camera camera_view.launch.py

NOTE: Select the /image/compressed topic rather than the base /image so that the images are streamed much more efficiently (at a higher rate).

Parameters

The driver exposes the controls supported by the camera as ROS parameters and all of them can be listed with:

$ ros2 param list /camera_node

Further, the ROS 2 CLI can be used to see what these parameters are for and which values are available and what they mean, with ros2 param describe command. One can get and set their values dynamically with ros2 param get and ros2 param set commands.

$ # Describe parameter
$ ros2 param describe /camera_node image_size
$ # Get parameter
$ ros2 param get /camera_node image_size
$ # Set parameter
$ ros2 param set /camera_node image_size [320,240]

Note: The following command can be used to check supported resolutions i.e. image_size of a particular video device:

$ sudo v4l2-ctl -d /dev/video0 --list-formats-ex

Calibration

The camera calibration yaml file can be placed in the $HOME/.ros/camera_info directory renamed and populated with the correct camera name.

Reference

https://gitlab.com/boldhearts/ros2_v4l2_camera
https://medium.com/swlh/raspberry-pi-ros-2-camera-eef8f8b94304