It is not "seeing" in the same way as visualising things. The way I would visualise assembling a flat-pack wardrobe or something feels totally different to this.
It is hard to explain. The best I can think of is sensing (without visualising) a shape or pattern. You cant actively "see" it in your mind (e.g. if I imagine an apple I can actively see an apple in my mind) - this is more fleeting and defies any focused thought.
Just like a mechanic is seeing or, a sportsman is seeing his next moves and so on.
Even blind people "see" the same way, they still have a visual cortex and understand spatial relationships.
So I'm pretty sure if someone did not have this type of "sight", they would have very low IQ.