| A Contour Tracking Problem [message #71128] |
Wed, 02 June 2010 06:04 |
jgrimmond
Messages: 4
Registered: September 2008
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Junior Member |
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I would very appreciate if I could get help on this problem. It is
mostly an imaging problem, but may involve some mathematical
issues. Hence the crosspost. Rather than be very general, I
will explain the actual example I am confronted with to keep
things simpler and clearer.
I have an image (digitally acquired), that represents the
contours of an unknown function. In this particular case, the
contours are interference fringes of a thin film and hence
represent contours of constant film thickness. I now wish
to get a map of the actual thickness, given that I know
the real thickness at some reference point and I can somehow
differentiate between going 'uphill' vs 'downhill'. This is just
the reverse of the usual plotting problem where one *knows*
a function z = z(x, y) and then gets a contour plot of z.
Assume that we can process the image to the point that
we have just black or white regions and so we can clearly
determine when a fringe is crossed while moving along a
particular direction.
While one can keep track of contour crossings as one moves
along a straight line, the part that I cannot get a handle on
is how to keep track of the contours and know when one is
back at a contour that one has already crossed. In my case,
the contours are closed and there are multiple local maxima
and minima to deal with.
Any pointers will be appreciated.
Thanks.
J. Grimmond
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