Displacement map values

I’m not sure how Reality Scan decides on the values of a generated displacement map.

Lets say I have a simple object relief that i texture project onto a plane directly above the object.
What value does the exr pixel have that’s closest to the object?
Does it depend on the size of the objcect/plane or just the distance between the object and the plane?
What determines the highest value?
The reason I’m asking is because we’re planing to generate normal maps from the displacement maps for a lot of objects and we’re trying to get a consistent result without eyeballing each map in an image editor. (We’re not using Reality Scans normal maps but that’s a topic for another post :).

Thank you in advance!