Find position and size of blob, opencv c++ ms visual studio, win7, 64bit

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I am building this system that detects/tracks a face(realtime). From that I want to measure som parameters from the eyes of the person in view(blinks for example). The tracking part is working well and I am able to get this output from the data:

You've might have seen my previous post here where I ask for help with the findContour method. it seems like this method doesnt want to work on my computer, (dont know why), so I have to find another way.

I've tried houghCircles, but the resulting circles becomes really strange with positions at -203942034 pixels or so.

So I wonder. What alternatives do I have to find the size and position of the (biggest, due to noise) blob in the matrix visible above.