Global Hackdays

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For our first hackday, we’re working to assemble dirt-cheap tangible interfaces, with the Trackmate project as inspiration. I’m really interested to see people try different solutions. Tracking software that uses tags (or “augmented reality,” if you want to use the more metaphysical description) is attractive because it can use things in the physical world. That means some opportunity for creativity.

We have two basic models for this project on Instructables. One is designed for maximum portability by using a clamp for the surface and eliminating the housing. As a result, it can use a conventional lightbulb. The other makes a housing and uses LEDs – and uses a picture frame for extra character. Now, personally, I’m a fan of the materials used in the portable version and the LEDs and housing in the other, but you’re welcome to go whichever direction you feel is best. Here are those two examples:

Trackmate :: Classy Hardwood CurioMore DIY How To Projects

Trackmate :: Portable Plexi CliffhangerMore cool how to projects

You won’t need much, but you will need some materials before you get started. Basically, you want:

1. A light source
2. A webcam
3. A housing of some kind (a box, or a stand, etc., which will put some distance between your surface and your camera and light.)
4. A surface
5. Some objects to tag (blocks, etc.)

Most of this is open to creative interpretation and hacks, but there are a couple of items that are pretty critical:

1. Webcam: The Sony PS3Eye webcam is currently the widely preferred camera for this sort of application, because it’s cheap, and — with the right drivers — extremely high performance. Game and toy stores carry it all over the place, and it lists for $40. GameStop the day before the hackday, anyone?

Windows drivers (heavily updated, lots of notes!)
Mac drivers (you want the latest binary version – grab it from CVS in the link on that page)
A Linux thread (more complicated for this camera, so you may actually want a class-compliant webcam for Linux … I’ll try it on my build, though)

2. Lights: If you want to put this in an enclosure, LED lights are what you’ll need; conventional bulbs are too large and too hot. Search “LED strip” and you’ll find some options. I opted for a shady-looking car accessory parts dealer, which is shipping from China. I’ve since learned the smarter way to go is a vendor called Environmental Lights. See their LED ribbon flex line, and look for a sample kit (cheap, 9″ worth) in superbright white-only (not the color changing ones. These guys also make the only IR LED strips I’ve seen, which you won’t need or want here, but are ideal for tracking applications that use light only and not tags. And they have some nice tutorials, as well! Those of you not in the US, you may need to check out alternative sources for shipping, sadly.

Other than that, of course, room for some creative thinking! Comment or contact me if you have any questions. A huge thanks to Nathanaël Lécaudé, developer of the Python-based multitouch PyMT project for tips on supply sourcing! And, of course, enormous thanks to the team at MIT working on Trackmate for the inspiration, as well as to Martin of ReacTable.

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