Wiimote as Multi-Touch Display Controller

Tmack writes "While hard-hacks with the Wiimote are somewhat old news, this particular implementation is quite interesting. Using the infrared camera on the Wiimote, pens with LEDs instead of ink, and an LCD projector, Johnny Chung Lee of Carnegie Mellon University has created software to use them as a (relatively) cheap multi-touch display. Any surface onto which you can project becomes an interactive multi-touch display, as demonstrated in the video at the link. He has the software available for download, along with some other neat projects. Lee has also documented another impressive Wiimote hack.

Wiimote is a Wii-Detector

[imstanny]

The Wii-mote is actually a sensor that is used as a remote. It doesn't just send a signal, but rather it 'sees' the location of the 'motion detection' bar. In the traditional usage, it has only 1 point that it detects - the bar. But if you have 'many of these bars' the Wiimote is used as a detector of multi-inputs.

Re:Wiimote is a Wii-Detector

[Paralizer]

The sensor bar has two IR points on either end to help with calculating things like distance. The wiimote itself can see up to 4 IR sources at any given time. So the multitouch interface would be limited to 4 pens, not that you'd need more than that though.

they have size...

[emj]

... you see how big/close they are as well, so it's not just position.

Re:they have size...

[slim]

... you see how big/close they are as well, so it's not just position.

No, the Wii software expects the Wiimote to see two IR dots (one on each end of the 'sensor' bar). Everything is calculated from these two points. X/Y position is the X/Y position of the midpoint between the two dots. Roll is the angle between the two dots. Z position (closeness) is the distance between the two dots.

Re:sure you can... Re:I can get one now?

[gallwapa]

semi OT, but...

A few notes if you're having trouble:

First, make sure your IR sources don't confuse the wiimote. Example: Opening my drapes on the window behind the TV on a warm, sunny day, made the wiimote useless.

Second, set the proper height for the "sensor" bar in the Wii console itself. It does make a difference, especially if you have a large TV

Third, make sure your batteries are properly charged. Don't wait for the warning to go to red. When it gets to 1 bar, put the batteries in the recharger.

The "IR Pollution" is the biggest factor affecting the performance of your wiimote, in addition to distance. If you're standing 20ft away, you may wish to get a separate wireless IR emitter ($6 on amazon)that you can mount somewhere closer in your room.

Hope this helps

Re:sure you can... Re:I can get one now?

[AKAImBatman]

I keep wanting to bash the thing against my coffee table because it won't detect that it is pointing at the screen.

Check that there are no bright IR light sources nearby. Sunlight and Christmas lights are two common ones that confuse the Wii Remote. Also make sure that your Sensor Bar is far enough forward that it isn't blocked at certain angles.

An easy way to figure things out is to go into the Wii Remote settings screen. There's a black and white image there that effectively shows you exactly what the Wii Remote "sees". You should see a few dots that do not flicker or go away as you move the remote around. If the dots disappear at any point during your tests, you may need to adjust your sensor bar.

If the lights appear to be working okay, but the remote is still confused, try turning down the sensitivity of the remote. That will encourage the remote to ignore light sources other than the sensor bar.

Re:I can get one now?

[Smidge204]

Just about any CMOS webcam can be easily modified to see only IR light. It involves removing the IR filter (usually a small glass plate with special coating inside the lens assembly) and adding a filter to block visible light (usually a fully exposed piece of film negative).

=Smidge=