| Re: A Contour Tracking Problem [message #71169 is a reply to message #71127] |
Mon, 07 June 2010 21:20  |
jgrimmond
Messages: 4
Registered: September 2008
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Junior Member |
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On Wed, 2 Jun 2010 06:56:36 -0700 (PDT), Chip Eastham
<hardmath@gmail.com> wrote:
> On Jun 2, 9:04�am, jgrimm...@yahoo.com wrote:
>> 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
>
> Do you have colors of polarization to tell
> when you are going "uphill" vs. "downhill"?
Unfortunately, no.
J. Grimmond
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