Use camera (photo) to measure distances ( and area)

[SteveJG]

This is a similar discussion regarding measuring from a Camera image; it might give you some ideas

• Recognize specific color area of an image (measure the width of a tree trunk from a photo) - #17 by SteveJG

A way to measure distance within a Canvas (thanks to Pythagoras ) Perhaps it can be adapted to your needs?

• Calculate Distance within a Canvas