• ROS (tested with ROS Melodic)
• OpenALPR

• Create a workspace directory, catkin_ws

$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws

• Prepare the workspace

$ wstool init src

• Copy the myrosalpr ROS package to the workspace, at ~/catkin_ws/src/

• Build the workspace and the package

$ cd ~/catkin_ws
$ catkin_make

• Install the package

$ catkin_make install

This package is a subscriber node that listens to the cv_camera/image_raw topic from publishers, performs license plate recognition using OpenALPR, and outputs the results in JSON format.

The executable for the package can be found at ~/catkin_ws/install/lib/myrosalpr/myrosalprengine.

Usage:

$ ~/catkin_ws/install/lib/myrosalpr/myrosalprengine --result result.json

where result.json stores the license plate predictions in JSON format.

This code has been provided under the 3-clause BSD License.