My imagination is very vivid. I often visualise an orb of light in my head, sometimes it looks more like a 3-dimensional version of a star. I see lots of images when I intend to see images and often I can let them flow very well with minimal effort. I often see dark scenes and nature because these are things I like, or maybe I like them because they are what my mind tends to visualise.
And sometimes when I go into visualisation mode, my eyes will move rapidly as if I were in REM sleep.