Like you describe I can visualize a lot of things, with fidelity, but it's still in my mind's eye (that is, a 'sense' rather than a physically represented image that's as apparent as other IRL objects). I can also hone in on details with my eyes open while doing other things. However I can't trace such things merely from this sense since they're not actually there for me. I can however leverage my draftsmanship skills to be able to focus on the mental visualization/sense and progressively draw from memory and for various familiar things visualize them on the paper but not as an optical manifestation.
I can't conjure up smell/taste experiences the same way, but I do have a sort of hollow visualization ability.
Edit: I read a few more comments, and it seems I'm not alone! Now I wonder whether this is common in the general population or just HN.
My impression is that individual differences lie much less in the actual mental abilities than in how people interpret and describe those abilities.
I used this often to recall if I did tasks. Just yesterday I forgot if I had washed my body when showering because I was thinking about something technical. I had to pause and thing, and I recalled seeing putting the soap in my hand. Not just some vague thing, more like a movie. Still no recollection of doing the motion though.
However when reading books or hearing tales, I've always struggled with the authors description of a place. Like I'll pick up on some early key words, and then construct the scene or location in my mind. Further description by the author hardly matters.
The weird part is I can get a really strong sense of being there, yet at the same time not really seeing it. It's really weird and the best I can describe it is that it feels like seeing or visualizing something. If there's an office with a red door, I know it's there, I can feel it's part of the location and it feels immersive, but I don't actually see or visualize a red door.
I think it’s more likely that others describe this abstract visualization as “seeing” although they don’t really see it, as opposed to them really seeing it as if it were real. As you say, it’s difficult to describe. It’s like a memory of having seen something, and people might describe that as really seeing (because it’s like a memory of really seeing), but in fact it’s not.
It’s like hearing a song or other piece of music in your head that you know well, and you can hum or sing along it, but it’s not like you’re actually hearing it.