Author Topic: Some questions for a newbii  (Read 3590 times)

Offline Kricket

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on: October 27, 2009, 02:18:32 PM
Hello all,

I landed on this site while searching for a relatively concise explanation of what's available/possible with a wii controller or two.  I'm experimenting with making a sports video game, and long story short, I thought it would be neat to try to capture data from real humans in order to animate the players in the game.  In other words, I'd like to hook up a bunch of sensors to key points on somebody, have them perform the motions typically used in the game, and record the motion of each of the points, to be mapped to an in-game character.

I'm a veteran computer programmer with a degree in math, but I don't have much experience with low-level stuff (electronics).  Is this sort of thing possible with a (or several?) wiiMotes?  How exactly does the wiiMote work?  I get that it receives IR signals, and talks to a computer via Bluetooth...I assume somewhere you have a signal and two receivers, or two signals and a receiver, and you triangulate...but I don't know much about what you can do with IR, how many receivers the remote has, how much grief I'd have to go through to get something working...

Any help would be greatly appreciated.  Thanks!



Offline boonjin

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Reply #1 on: October 27, 2009, 06:46:26 PM
Hello all,

I landed on this site while searching for a relatively concise explanation of what's available/possible with a wii controller or two.  I'm experimenting with making a sports video game, and long story short, I thought it would be neat to try to capture data from real humans in order to animate the players in the game.  In other words, I'd like to hook up a bunch of sensors to key points on somebody, have them perform the motions typically used in the game, and record the motion of each of the points, to be mapped to an in-game character.

I'm a veteran computer programmer with a degree in math, but I don't have much experience with low-level stuff (electronics).  Is this sort of thing possible with a (or several?) wiiMotes?  How exactly does the wiiMote work?  I get that it receives IR signals, and talks to a computer via Bluetooth...I assume somewhere you have a signal and two receivers, or two signals and a receiver, and you triangulate...but I don't know much about what you can do with IR, how many receivers the remote has, how much grief I'd have to go through to get something working...

Any help would be greatly appreciated.  Thanks!

Hi,

Using the 2 Wiimotes you are able to triangulate the IR signals in the 3D space but from my experience, you will have the following limitations:
  • Each Wiimote will only output the first 4 IR dots it detects - You may need to have blink this IR LED at high frequencies so the Wiimote is able to capture more than 4
  • Drawback of the above is, the intensity of the IR signal will drop due to the reduced average power.
  • Furthermore, the Wiimote's IR camera extrapolates the data from a low resolution camera. Therefore, you may have low triangulation accuracy with the above techniques
  • Differentiating the detected IR points - You may need to use some signal to differentiate the points depending on your set up.
  • FOV (Field of View) of the Wiimote is less than 45 degress - You may need a big space for the product if you are capturing movements of people. And the further the IR source, the lower the intensity of the IR source detected.

Therefore, if you are not planning to capture the motion of 4 points or less then using the Wiimote might be a simple solution with the above limitations. Otherwise, there will be a lot of tinkering and experimentation required .

Regards,
Boon Jin

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Offline Kricket

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Reply #2 on: October 28, 2009, 03:32:05 AM
Hello,

Thanks for the reply.  I'm not afraid of a little tinkering to get something workable.  I could probably come up with a programmatical solution to follow the paths of the points.  I could compensate for lack of accuracy by repeating the test several times for the same movement, and taking an average.  For rapidly blinking the lights, I assume there might be some sort of electronic part that would do the trick?

Another thing I thought of - IR requires line-of-sight to work, right?  Perhaps a setup with 4 wiimotes (2 here, 2 there) would help with that...

Otherwise...can you point me to a good code library for getting data from the wiimote?  Preferably not C#/.NET...

Thanks for your help.