An RGB Encoder is a device found at most video studios that takes RGB input,
and puts out NTSC component video. Grass Valley and others produce them, good
ones start at $3000 and up. I haven't seen the SuperGen in action, but I heard
that it's good.
Blaze Harvey used the aircraft and spaceships that are supplied on the
VideoScape 3D data disk. It also used one of those "ShowTime Video" processors
to help clean up NTSC. It looked O.K. (not Pro, but good).