Physics is a Bitch
Well, not really. It’s just a pain when the problem was painfully obvious once you realized what the problem was in the first place.
We’ve been working on our interactive table for most of the summer (unfortunately as a part-time gig, rather than the full-time attention that it demands). It’s a hard project, but we’ve been slowly chipping away. There aren’t any of those breakthrough moments where everything just falls into place, it’s just an iterative grind.
I was choking on the guts of the table for about three weeks where we need to have two projectors, two mirrors, two cameras, and a large computer. I kept moving things around in Sketchup trying to figure out the projector throws (an aside rant: why is there no 3D software that lets you model light? Not just the results, but the actual beam of light and have it visually bounce off a surface? everything is a hack.) and coming up with a solution in software that wasn’t working in real life.
The important bit to know is that most projectors don’t project evenly outward. They’re designed to sit on a table or a desk, so one side of the projection is pretty horizontal rather than an even cone.
So, I took a left turn and applied my bold papercraft skills finely honed in kindergarten. I printed out the projector throw and cut it out of a piece of paper. It was great because there was no way for the throw to not work or bend incorrectly. Even better, it was quicker to make changes than doing it in some 3D app (arguably I was using the premiere 3D app, real life).
After about 10 minutes of playing, I stopped and gave a long hard stare at what I was working on and just started laughing since it was painfully evident what my problem had been all along for the previous couple of weeks. I had one of the projector throws rotated 180 degrees and while I had thought I’d correctly measured that angles of reflection, there was no arguing with the paper that I had been getting it wrong all along.
So, lesson of the day: Got an impossible problem and no solution is working correctly? Get out the paper and scissors and do it old-school. Ironic that this would have been easier to figure out 100 years ago.