Knob/dial values from photograph

How would you approach the problem of capturing the values of rotary knobs on a machine from a photograph?
Possibly capturing something like angle of knob indicator, but how do you set up a pipe line to recognise the knobs and then determine their position

Hi ptah hope all is well?
This person is trying to recognise certain features on pipes, maybe you could try a similar approach.

Cheers mrfabulous1 :smiley::smiley: