Wiimote Whiteboard - FAQ and Adv Discussion

A lot of very smart people have written in questions and suggestions and I think a lot of them are very clever and worth sharing... and I'd like to add some of my own expansions on what I showed in the video. Like they say, 2 brains are better than 1.... it turns out several thousand brains are even better. This post will be REGULARLY EDITTED to add new ideas as they come in. I know it breaks the RSS model, but I don't want to make a new post for every new idea. Sorry.
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My Bluetooth adapter and LEDs - Though it is reported to work with many bluetooth adapters and chipsets, I've been using this one sold by SparkFun electronics. The IR LEDs I use are Vishay TSAL6400s running at 100mA available from Mouser.

Tip switch - Instead of pressing the side button to illuminate the LED, a tip swtich could be added to illuminate when pressed on a surface. Though, it's mechanically harder to make and finding the right level of pressure for activation can be hard, especially if your surface varies (ex: whiteboard vs carpet)

Can you do this with a webcam? - The wii remote contains a 1024x768 camera with built-in hardware for IR blob tracking of upto 4 points at 100Hz. This significantly outperforms any $40 webcam I'm aware of. It'll work with a webcam, just not as well and not as easily.

Rear-Projection - using a rear projected surface, works great. The software will automatically work as-is so long as your pen is bright enough to shine through the projection surface. The wiimote gets a unobstructed view of the screen which eliminates occlusion problems and maximizes tracking resolution. Though, actually building a rear-projection wall or table can be a little difficult if you don't already have one.

Pressure sensitivity - wacom tablets give nice pressure sensitive behavior. Doing this with the wiimote whiteboard will be tough, at least through the camera data. The brightness of the LED varies significantly depending on angle, surface reflectivity, and distance. Any pressure data based off birghtness will not be reliable. The data could be transmitted via a high-frequency IR channel (like remote contol data) to an IR reciever mounted on the wiimote. (see "Right click" for more)

Right Click - any right click signal based off brightness is not likely going to be reliable. Additionally, using multiple LEDs (1 - left click, 2- right click) won't work at all distances and orientations as the LEDs get too close for the wiimote to distinguish them. The RIGHT way to do this is to use high-frequency IR data transmission (like remote control data) to an IR reciever. This will also give you a way of potentially getting pen ID - which is VERY powerful and may be a future project. Though, this requires quite a bit more hardware.

Multiple wiimotes for better tracking - if you have a large surface, you could have multiple wiimotes covering different areas to keep tracking reslution high, or have the wiimotes cover the same area to avoid occlusion problems, or do some interpolation of the data for higher accuracy. All possible, just with the smarter software. Doing this myself is probably not going to happen, but the source is freely available.