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Unread 18-02-2013, 20:42
jwhite jwhite is offline
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Axis Vision hue / threshold / white balance experience

One of my student programmers requested that I post a what we have learned about the C++ vision tracking process in case it helps anyone else.

We initially had a 206, which we later swapped out for an 1101, thanks to the incredible kindness of 1816. We were having a lot of trouble with it and the Smart Dashboard, which may have just been the Smart Dashboard:
http://www.chiefdelphi.com/forums/sh...d.php?t=113519
The 1101 now seems to be working well.

We have a green led light that we shine, and try to find the reflections using the C++ vision sample code. Our first struggle is to just make the image coming from the camera match the sample images provided in the sample code; we initially spent a lot of time fiddling with the camera trying to make the reflected image 'green'.

We find that every environment we go to has different lighting conditions, and we literally have to adapt the camera for each one. What we now do is load up the camera and play with the exposure and white balance settings until we feel we've got a good, strong color. It can be green, it can be blue-green; we don't care. Then we take a screen shot of it, and throw it into MS Paint. Using the eye dropper, we pull out the Hue (using edit colors).

Then, in the code that constructs the threshold, the first two terms (default 60,100) bracket the Hue. We find that our light sometimes ends up looking more blue than green, which is a Hue more like 120. So for some lighting, we end up with a hue range more like 75,130. We haven't really played with how narrow we can make the band and still have things work.

Cheers,

Jeremy
 


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