It would probably be good to specify which you're talking about too... computer generated images, and 3D. Because I thought of another example, but it's not older than trek. There's some very basic computer graphics generated in the movie "The Thing" (where you see the doctor's computer run a simulation of the alien cells taking over dog cells). They are flat, however. I just realized there were also probably some flat, computer generated images in the film "2001" which is (ACK!)exactly as old as me. It's been a while since I've seen the film though, might have it confused with something else, but I would think HAL's voice pattern display would count as computer generated, but not 3D.