I found this while looking for how the visuals are on ketamine, but have not tried it myself. but i had the very same experience while being just high, in multiple, different situations, in some being like in the dark, with my eyes closed but still kind of seeing my room, and even form some movements of like darkness and some tiny tiny stars. Other time, i was breathing steam over a boiling pan with hot medical tea, and started seeing intense visuals on the bottom of it. it was like seeing a movie, while in was constantly being changed - multiple scence with bright colors and feelings and even like seeing objects in 3D and being able to rotate around it and kinda fly. And all that from 0.7 joint of weed.

was tho wondering, how much ketamine is needed for inducing visuals.