Given a metal object (let us say a perfect planner uniform surface) that has been exposed to external environment factors such as sun, wind, rain and others for couple of years.
This object has been changed in a way or another. For example, the surface which was perfectly smooth should have been damaged a bit. Those changes may not be visible to the naked eye (or maybe but let us assume that it is not).
Hypothetically, the damaged (changed) surface should not be uniform anymore. For example, the external environment factors will not affect each region of the surface in the exactly same manner.
Given that the previous assumption is true, and using a special camera (non visible; such as infrared, ultraviolet or any other spectrum range), the goal is to get a unique map for that surface that is robust even if the shot was taken from different angle or distances.
More clarification: The surface at manufacturing moment was smooth and uniform. It is simple metal surface that if it was captured by any type of cameras, the result will be uniform (you can not tell which part is which. For example:
After the external environmental factors have affected the surface, I am guessing that the the surface optical response to some spectrum range could be like:
- Is the mentioned assumption true?
- What kind of optical response is needed for this task or in other words what type of optical sensor is needed?
- If all of what were mentioned are not correct or not applicable, what other physical phenomena that I can rely on to detect the mentioned unique map of that surface (any simple clue is much appreciated)
Edit - Clarifications:
I do not need topographical map. I need any map of the plate that is unique (so topographical map is an option but not the only one).
My goal, for simplicity, is to capture those unique maps for, let us say, 100 pieces of metal and store them in a database and then be able to capture a unique map of anyone of them and compare it to the database and know which one is it (note: the period between the first and second capture is less than day and maybe few hours. So, I am assuming that during this period no noticeable change will occur).
Microscope is not an option, the images are captured 1-2 meters far from the piece of metal.