Consider IOU instead of point in box

[robmarkcole]

An IOU calc would give the % overlap of a detected object bounding box with the target area, which is a more flexible detection approach than specifying that the centre of the object must be in the box. You could using IOU say 'if any part of the object is in the target area, detect it', or 'if all of the object is in the box detect it'. A default of 50% sounds sensible

See https://github.com/blakeblackshear/frigate/blob/master/frigate/util.py