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honsey
04-19-2010, 01:18 AM
hey there.


i have a problem with tracking two ir-sources (leds). i think the ir-sensor is supposed to put the positions and sizes of the leds in /ir/xys/1 and /ir/xys/2. sometimes this works perfektly, but from time to time /1 or /2 is empty and the position gets stored in /3 or /4.


hope somebody knows how to deal with this / thanks in advance!


hans

camille
04-19-2010, 07:55 AM
Hi Hans,


The Raw IR mode returns what the Wiimotes has processed with the minimum of change. What you see here is a result of the Wiimote loosing track of your two initial dots and trying to track them as a new group. Remember that the IR bar has 4 LEDs which shows that the dot tracking algorithm inside the Wiimote has been clearly designed for that application.


So if you track less than 4 dots, as you noticed it can happen that it returns non ordered tracked dots. What you can try is:

1. Increase the strength of the IR light source(s)

2. Move the light source slower

3. Merge the /1 /2 and /3 /4 events. Just ignore the fact the Wiimote can produce /3 /4 events by respectively routing those events /wii/1/ir/xys/1 and /2. If you are using MIDI you could also assign the same events to /3 and /4 that you did for /1 and /2 instead of using a OSC routing.


Best,

Cam

honsey
04-23-2010, 12:37 PM
thanks camille for your quick reply!


i think i found the problem: i already tried to increase the strength of the leds by pulsing them. because of that faster movements got tracked as several points.


i'll try to use two (or more – depending on my duty cycle) alternately pulsing leds to serve a (faked) constant led for the camera.


do you have any information about whats the time-resolution of the wiimote ir-cam? the output is 200Hz – thats what i found out, but is it the input resolution too. or even higher?


are there any projects you know, that use the wiimote to track positions over distances of 5m and more?


have a good one & merci!

camille
04-26-2010, 10:54 AM
Hello Honsey,


The Wiimote camera sends updates at the same rate the Wiimote sends data reports, something around 60 hz (17 ms).

But that does not mean that the camera is updated at this rate, or that the sensors of the camera have such a fast refresh rate. Actually, the refresh rate of the camera has not been measured, so I can't tell you anything precise.


There is a project of a friend who paints on huge walls with the Wiimote, but he uses spots and not IR leds to generate enough IR light.


Best,

Cam