USB Mono Camera ROS Node

This is a camera ROS node for USB mono cameras (Webcam), based on OpenCV VideoCapture API. The ROS node publishes raw image and its camera_info.

NOTE: This ROS node currently is tested only with Logitech C920 and C270 webcams in ‘YUYV’ (YUYV 4:2:2) mode. ‘MJPG’ (Motion-JPEG) mode is not yet enabled and tested. To use the camera in ‘MJPG’ mode, it is recommended to use ‘gscam’/’gscam2’ ROS package instead.

Usage

1. Camera Calibration: A Python tool for camera calibration is provided: $SDK_DIR/tools/mono_camera/camera_calibration.py. This calibration tool takes a set of checkerboard images captured with the target USB camera, and generates camera_info.yaml. Example calibration images are provided. While setting up the Docker environment, the calibration images are downloaded under $HOME/j7ros_home/data/calib_images. Below is the usage of the camera calibration tool, and for examples, please see $SDK_DIR/tools/mono_camera/calib_C920.sh.

   usage: camera_calibration.py [-h] [-p PATH] [-e EXT] [-r PTS_ROWS] [-c PTS_COLUMNS] [-s SQUARE_SIZE] [-v VISUALIZE] [-f SCALING_FACTOR] [-o OUT_FNAME] [-n CAMERA_NAME]
   
   optional arguments:
   -h, --help            show this help message and exit
   -p PATH, --path PATH  Path to the directory storing images for calibration
   -e EXT, --ext EXT     Extension of the files
   -r PTS_ROWS, --pts_rows PTS_ROWS
                           Number of inner corners per row
   -c PTS_COLUMNS, --pts_columns PTS_COLUMNS
                           Number of inner corners per column
   -s SQUARE_SIZE, --square_size SQUARE_SIZE
                           Size of a square (the edge, by mm) of the checker board
   -v VISUALIZE, --visualize VISUALIZE
                           Visualize the checker board or not
   -f SCALING_FACTOR, --scaling_factor SCALING_FACTOR
                           scaling factor after reading images
   -o OUT_FNAME, --out_fname OUT_FNAME
                           Path to the output file to store result (in YAML format)
   -n CAMERA_NAME, --camera_name CAMERA_NAME
                           Camera name
   

2. Rectification Map Generation: A Python tool for generating rectification map is provided: $SDK_DIR/tools/mono_camera/generate_rect_map_mono.py. This tool takes the camera_info YAML file, and generates a binary file for undistortion & rectification look-up-table (LUT) which is required in offloading the undistortion/rectification on J7 VPAC/LDC hardware accelerator. Below is the usage of the tool, and for examples, please see $SDK_DIR/tools/mono_camera/calib_C920.sh.

   usage: generate_rect_map_mono.py [-h] [--input INPUT] [--name NAME]
   
   optional arguments:
   -h, --help            show this help message and exit
   --input INPUT, -i INPUT
                           YAML file name for camera_info. The file should be stored under ../config folder
   --name NAME, -n NAME  Camera name
   

3. Build the USB mono camera ROS node

   cd $ROS_WS
   # ROS1
   catkin_make --source /opt/robotics_sdk/ros1
   source devel/setup.bash
   # ROS2
   colcon build --base-paths /opt/robotics_sdk/ros2
   source install/setup.bash
   

4. Launch the mono camera node

   # ROS1
   roslaunch mono_capture mono_capture.launch
   # ROS2
   ros2 launch mono_capture mono_capture_launch.py
   

Launch File Parameters

Parameter	Description	Value
model_str	Camera model string	string
device_name	camera device name. Typically /dev/video1 on the target with TI Edge AI	string
camera_mode	Camera mode	'FHD' (1920x1080)
_	_	'HD' (1280x720)
_	_	'VGA' (640x480)
frame_rate	Frame rate at which raw images are published	int
encoding	image encoding	'yuv422' (default) or 'bgr8'
topic_ns	topic namespace	'camera' (default)

NOTE: When encoding is set to ‘yuv422’, the pixel format YUV422::YUYV from the webcam is converted to YUV422::UYVY format considering the compatibility with LDC hardware accelerator.