I've been recently doing some experiments with a camera, projector and Processing. I made some simple sketches and project them to a screen at high framerates, capturing the whole projection with a long exposure photo. Some of the results are here: www.generativephotography.com

I'm specially intrigued about Centered and Framerated sets and the reason why glitches appear as they do. I described some of the experiments I made  here and  here, but there is still many questions without answer.

I don't know much about computer graphics and I'd like to know why these glitches are generated, what can affect it's variation, etc. It seems there are glitches while rendering, and also because the asynchrony between the framerate of the sketch and the refresh rate of the projector.

- Why sometimes there the rectangles (or circles) are double width?

- Why the glitches appear on a different height of the screen each time I start the sketch, but the same height if I run the sketch without quitting?

- Sometimes part of a rectangle (or circle) is exposed twice or three times the time of another part. Is this because the rendering or the asynchrony with the projector, that skips part of the information that it receives from the computer?

I'd appreciate any suggestion or comment on that. Thanks a lot!