Some guys with lots of time on their hands, or a pressing need to complete their academic research papers have devised a way to make a projected image show correctly on a screen/surface at varied angles. Specifically, these smart people are: Johnny C. Lee, Paul H. Dietz, Dan Maynes-Aminzade, Ramesh Raskar, and Scott E. Hudson.

So, PowerPoint Rangers, no need to fret when the heads of the audience will absorb the light energy you desired to show on the screen! Just hang the projector so it has a boresight view of the screen.