Publish CameraInfo, when available.

[jack-oquin]

I am thinking of writing a Python camera_info_manager module, with a subset of the full C++ implementation.

With that, the camera driver would use a standard camera_info_url parameter to access calibration information for the appropriate device.

[jack-oquin]

I plan to fix this by modifying the axis_camera driver to use my new camera_info_manager_py package.

That introduces an additional package dependency, but seems much cleaner than including the Python camera_info_manager module inside axis_camera. The camera_info_manager_py package itself has minimal dependencies.

In theory, other Python camera drivers could also use that package, but I doubt there are any others right now.

[mikepurvis]

Hey Jack— that would be great. When I was putting this node together originally, I looked at implementing CameraInfo, but it wasn't a necessity for our initial users.

[jack-oquin]

As you can see, the changes to the driver are simple.

Please note that camera_info_manager_py does not yet handle the set_camera_info service call. I intend to implement it soon. That change should have no effect on axis_camera, except allowing the driver to immediately start using a new calibration when camera_calibration completes.