Seems like these multitouch tables are showing up everywhere. This one is done with a cute video that brightens up the build process. Best of all these old projectors are being thrown out in favor of the smaller, higher resolution and more portable versions.
Thanks Ravi
"The image processing software analyzes inferred light from the web camera and treats any light detected as a separate input source. Then this software sends the data to any other applications that have the ability to use the input (like a google maps plug-in). The multitouch table simply acts as a device that sends out IR light beams, so when a fingertip incepts them it appears as if the fingertips are producing Inferred light."
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awesome montage:)
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Excellent production values.
I did something similar once, but didn’t use IR LEDs. The incandescent lamp of my projector produced something on the order of 100W of IR, which would completely overwhelm any IR LED. In fact, unless I missed something, I’m surprised your design worked at all, after reflection from the undersurface of the acrylic top. Perhaps your webcam was sufficiently off-center to avoid direct reflection.
To reduce projector IR, I used a 1990s transmissive LCD screen designed for use with an overhead projector, instead of the video projector I’d planned to use. I didn’t use a transmissive (classroom-style) overhead projector, but a reflective travel unit which I sometimes see for $20-30 on eBay (Apollo VS3000, not to be confused with Apollo V3000, which is transmissive) Here’s modern model that illustrates its layout:
http://www.buyonlinenow.com/viewproduct.asp?sku=APO4000
A reflective overhead projector puts the light source in the lens head, projecting down onto a shallow parabolic mirror under the base glass on which the transparencies are placed. It disassembles easily for travel and experiments. If necessary (it wasn’t, in my case), I could have taped a IR sheet filter to the base glass, and used external IR illumination.
I hope my description makes sense, and helps other who wish to expand and develop on your work. When I was playing with this ca 2003, the available Open Source software wasn’t adequate for more than a demonstrator. What tracking software did you use?
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