District of Columbia Code Section 22-3312.01. Defacing public or private property.

It shall be unlawful for any person or persons willfully and wantonly to...write, mark, draw, or paint, without the consent of the owner or proprietor thereof...any word, sign, or figure upon:

(1) Any property, public or private, building...or facility, dwelling or structure of any kind including those in the course of erection; or

(2) The doors, windows, steps, railing, fencing, balconies, balustrades, stairs, porches, halls, walls, sides of any enclosure thereof, or any movable property.

We don't have clear precedent about this exact act of projecting images onto a building, but we do know that chalk markings, which are not permanent, are included in the scope of graffiti which is prosecutable. But chalk markings are physically real, whereas light images are not.