What's the word or name for a person who can naturally & accurately estimate measurements such as size, capacity, ballance & angles?

I'm sure I met someone like this a few years back & they provided me with a single word/name for the "condition". I say condition as the person who this affects automatically, & sometimes to the point of frustrated distraction, will be able to see (can't ignore) the smallest discrepancy in any of these measurements within their environment & will also accurately estimate correction. I'm not just talking about noticing a skewed wall mirror but rather an acute & often minute sense of balance in their surroundings.

Solution 1:

A related word, although perhaps not the one you want, is savant, in the sense of a person exhibiting savant syndrome. (Typically, such people have a disability that savant skills partly offset.) The wikipedia article on this topic mentions spatial skills as among the “five major areas” for savant skills. It also says:

No widely accepted cognitive theory explains savants' combination of talent and deficit. ... Another hypothesis is that savants hyper-systemize, thereby giving an impression of talent. ... Also, the attention to detail shown by many savants is a consequence of enhanced perception or sensory hypersensitivity in these unique individuals. It has also been confirmed that some savants operate by directly accessing low-level, less-processed information that exists in all human brains but is normally unavailable to conscious awareness.

On another tack (suggested by other answer) the term eagle-eyed describes someone who is perceptive and has excellent visual acuity.

Solution 2:

There is a French expression, "avoir le compas dans l'oeil", for just what you describe. This would be roughly translated as "having your eye [accurate] as a compass" and means that you can just "see" what other people will have to measure.