I was friends (more aquaintances now since I haven't seen him for quite a few years) with an incredibly talented artist / illustrator. I worked with him for a period and would place him more than anyone else I have ever met in the genius spectrum based on a number of factors. One of them is that I know that he can vizualize fully formed images, to the extent that some of his work is just transcribed directly from what he sees in his mind.

I have never been able to do anything close to this, and similarly have self-diagnosed as much weaker in this "power". I mean I can visualize things in my mind but it is fuzzy and fleeting, like focusing on any detail collapses the field of view.

This episode of radiolab about a musician who can maintain a 3d mental image of four orchestras playing at once always stuck with me, and seems relevant to this topic:

https://www.wnycstudios.org/podcasts/radiolab/segments/30142...