Persistent Vision Programming Notes - Andrew Linn

I got this demonstration from an ad in a magazine. They were selling Frisbees with programmable lights, you enter a message and throw the Frisbee, and people can read the message as it flies through the air.

I had been trying to find a way to demonstrate animation, but was not satisfied with the results I was having, they were too jerky and I didn't have the artistic ability to create the graphics. Persistent Vision allowed me to be able to show the concepts without having to become an artist.

When the program begins, it is displaying a 4 frame movie at 5 fps (frames per second), too slow to see the message spelled out by the dots. 16mm film plays at about 8 fps and most movies played over the computer are 15 fps. The human eye takes pictures at about 20 frames per second, movies in the theater are played at 24 fps, and television is displayed a little differently, 2 fields every 1/60th of a second, or roughly 30fps.

This animation is different from most, in that each frame is displaying a picture grossly different from the others, and one frame is completely black. Given that computer screens have different display capabilities and refresh rates and processing speeds, operating systems, and other programs can affect the rate at which these frames are displayed as well.

Original Director 8 source code if you have questions, please e-mail me at: alinn@willamette.edu