Forums > MaxMSP

cv.jit.features2track question

September 29, 2010 | 9:17 pm

Hello,
I was hoping someone could help me with a little problem I encountered while using this object.

Basically, I am trying to track the Iris of the eye and while it works great, when the person blinks, all the little dots generated by the object to track go all over the place. Is there a way to control their sensitivity?

Below are pictures of the Patch Before I blink then what happens after I blink.

Thanks

[attachment=142659,1192] [attachment=142659,1193]

Attachments:
  1. After_blink.jpg

October 3, 2010 | 8:05 pm

Hmm, seems to be the problem with cv.jit.track, once something passes in front of your tracking point you are scuppered.

Sorry if you already know this, but eye tracking is normally done by shining IR light into the eye and then using an IR camera to see the reflection from the cornea/pupil. You can make your own IR camera and IR spotlight easy enough and I guess you could use something like blob tracking.


October 4, 2010 | 12:50 pm

Is there a way to lower the sensitivity of cv.jit.track? Or maybe lock it in place?

Is there a site that shows how to make a proper IR camera and IR Spotlight?

I’ll definitely try blob tracking and see if that solves the problem.


October 5, 2010 | 8:18 am

Not that I know of, maybe with some clever patching you could compare frames and get it to ignore the ones with too much difference ie blinking, but its not something I have tried or would know where to start with.

Regarding IR cameras, well you can use the security type cameras designed for night time use with a ring of IR led’s around them, and then just stick an IR filter over them to stop visible light, but you need some sort of hardware interface as they are normally BNC connection or maybe RCA. However a cheap option is to convert a normal webcam by taking out the IR blocking filter and putting an IR filter in to block visible light, this can be a proper filter or a piece of camera film or floppy disk, and I’m sure I’ve seen IR spotlight kits from Maplin. Here’s a good tutorial of how to adapt a PS3 eye camera:

http://createdigitalmotion.com/2009/08/trick-out-your-ps3-eye-webcam-best-cam-for-vision-augmented-reality/

Here’s some other helpful stuff:

http://cycling74.com/2009/10/26/making-connections-camera-data/

http://cycling74.com/forums/topic.php?id=25607


October 5, 2010 | 9:07 am

Hmm, I’m having trouble getting a security camera to read in Jitter, but I’ll let you know how it goes!


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