I do suspect "visions" can come from different sources as well. I've worked at an ayahuasca retreat center and have drank about 500 times so had some opportunities to investigate this. My vision is typically very "closed" (often it is just a massive intuition increase, it takes me a huge dose to get really into the visionary aspects). I have had visions seemingly from the top of my head (these are the most intense, all encompassing for me), in my "mind's eye"/imagination, in my normal visual field, and from my heart space, and sometimes a mix of all of it. My big suspicion is that DMT induces a type of synesthesia, a mixing of all of the senses, plus intuition, thoughts, and memories, plus a big increase in sensitivity (meaning what we see/feel is not precisely a hallucination).