1 - Theory > 2 - Setup

Hardware

Placement...

If you're building exactly to our dimentions with the parts we used, the configuration below is what we found works best. Any other modifiactions will require something different. The goal is always this:

  • The projector covers your display area without skew and hopefully without cropping the projectors throw area.
  • Your camera can see the entire display area without much of the frame. The closer you crop your display area, the better your "touch resolution" will be.
  • The IR flood lamps together cover all of the diplay area with even distrubution. Extremely important!

This will certainly be the most frustating part of the project. Find a temporary soltion that works best, then everything must be secured in as firm a manner as possible. You don't want bumping of the box to throw off all your careful calibration!

Here you can see the placement of every item in the box.

  • Projector Lens must be in the center to avoid skewing the image. The back of the projector is resting on the support, with the threaded feet fully extended.
  • 4 LED clusters must be in each corner, pointed at the opposite corner to maximize their throw distance.
  • The camera is placed so it can see entire display area. We taped it to a spare piece of wood and taped it down to the base. You may want to screw it down.
  • The mirror is resting against the side panel and has glued down rests on the bottom that stop it from sliding.
  • The cables are taped out of view of the camera, projector and IR floods and power bars are taped down to the base.
  • Once you have the placement of everything finalized, you'll want to cut out holes for ventilation of the projector (it gets really hot) and a hole for your cables.

Any setup will require a lot of fiddling, but fiddling is critical. If the image is skewed, so is everything in your applications. If one of your IR flood lamps isn't positioned correctly, you could get dark spots where touching will be hard detect or a bright spot where you could get "false blobs". Play with every factor and take your time! Also, take head of these warnings:

  • Don't cut a round hole in the panel you take off as your cable hole. Think about what happens when you thread all the cables through and then take the panel off.
  • Things will get hot in there! The scent of pine blowing out of the vent serves as nice air freshener, but all electronics in there are sensitive to heat. Particularily the IR flood lamps. If condensation builds up, you'll start getting werid flickering dark spots. You may want to just remove the cover so condensation doesn't build up underneath it.
  • Without a good camera, any application you make or use will be quite frustrating. Don't accept less that 24 fps, and it's best to have 30 and up. We found that the PS Eye was the only camera with the aperture to get enough exposure of infra-red light to be able to run at upwards of 30 frames.
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