Originally Posted by toly
Rear view can clearly show if the ball is above the head or not.
Not completely. Side-to-side is shown but forward-backward is not. Above view gets side-to-side and forward-backward but not the height. Camera gets 2D where the lost axis is along the camera's line-of-sight.
There are hardly any HSV camera views of tennis strokes taken from above on the internet. I have not seen any except the FYB videos from a few years ago. I wonder what the set up was, cherry picker?
Videos from above might show what is going on with supination on the serve.