Graffiti – often seen as a bad thing; vandalism (I for one, am a fan for the most part). Then there is “non-intrusive” graffiti, that has a temporary, transient and digital component. Light painting. An act in space and time, that afterwards only lives digitally. The documentation of the act is the only evidence. So though I hate that term – it is a sort of performance art. But the value is both in the moment of making and the “eternal” still life that lives on digitally.
You will never know if it is “real” or not; it could well be entirely digital. But I do not think that is the point. The lines of light are fingerprint of people. Someone did it, someone was there, but it is also empty of life. “I am here”. Where emphatically, there is no one there.