PanTilt | Raspberry face tracker with Pan/Tilt | Computer Vision library

The issue you're having here is that memory is (generally) not shared between portions of a multiprocessing python program. In this case, scan_on is a local variable in your manager.py script, which is then re-instantiated in the visualization.py script.

To share data between Processes, we can use Values. These are objectified values that allow sharing state between Processes by simply passing it as an argument.

Why? Simple values like integers and booleans are copied when you pass them into a function, rather than maintaining state across their multiple instances. The Value object, however, simply passes a reference to the value rather than a direct copy.

Though I don't see where you're calling visualize_boxes_and_labels_on_image_array(), here's a start: