OF COURSE as soon as I typed a request I immediately found some sites:
https://beautifultrouble.org/toolbox/tool/guerrilla-projection
https://thedemlabs.org/2022/11/19/how-to-project-a-message-on-a-building/
https://blog.witness.org/2015/03/video-projections-illuminator-art-collective/
If anyone wants to share their own tips and hints, that's still awesome, though possibly not necessary now that I found some info (above).
Original message below (no longer relevant):
Just out of random curiosity: does anyone on #mastodon who knows about such things feel like writing an explainer for how to prepare, deploy, and maybe disappear after projection-style street art? Like projecting "Yay America" on the Washington Monument, or "Hi Mom" on the wall of the local city hall, that sort of thing?
What equipment does one need? What software? How to set it up and power it? These are questions certain people might have.
(A quick DDG search didn't show me anything except generic "how to use projector" sites so far, but I'd also be happy with a link to a site with info about this; I'll keep searching, and if I find things I"ll replace this message with links to what I find).