Author Topic: IR Illumination for finger tracking.  (Read 3951 times)

Offline s0l

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on: September 02, 2008, 11:24:02 AM
Hi all,

i find there is a lack of clear technical info about the finger tracking illumination technique and i wish to try to aggregate all relevant info in one single thread.

People seem to say that the recommended iR leds are made by Vishay ; i had a look at Farnell parts dealer and there are many variations of their 5mm iR leds.

There are 100 and 150 ma models. Wavelenghts available are 870, 875, 940 and 945 nm. Angle of visions are 20, 24, 34, 44, 50 and 60.


-Do we know what power and wavelenght the diodes in the Wii sensor bar are?

-Supposedly we should go for 945nm, 50 or 60 and 150ma right?

 

Wouldn't a diffused infrared laser diode be more efficient than leds? You know, putting a diffusing filter in front of it so the beam becomes conical...Though i guess it'll be more expensive.Much more expensive.

Probably going with a glove with leds at the tip of 4 fingers is the best solution for tracking reliability.

I will edit this first post as questions are answered so all important info is grouped right here.

Could those who are satisfied with their arrays post info about their construction/origin and their detection range relative to the wiimote?

Feel free to post advice or questions until then!  :D

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Update 1 : NUIGroup's boards ( http://nuigroup.com/forums/ ) are full of very useful info, they seem quite technical since they're developping unlimited blob multitouch detection and they found out that iR cameras "see" better the 850-870nm wavelenghts than those higher ups. Concerning the beam angles, the wider the beam the weaker the overall light intensity but the larger the detection area. Which is quite logical when you think about it ;). The original Wii wensor bar packs 5 leds at each end soldered as follow :

/ ||| \

Therefore the 2 iR sources are created by 5 leds emitting in roughly a third of a circle. No info yet on the original led specs though.

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« Last Edit: September 02, 2008, 03:32:38 PM by s0l »