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Re: Iso-contours at maximum/minimum levels [message #64961 is a reply to message #64891]

Mon, 02 February 2009 08:54

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Gianluca Li Causi writes:

> I thanks you for the interesting discussione and I agree with David
> that the word "contour" means a line that "encloses something", but
> still you've not given indications for a working "imprint" function,
> which is what I need.
>
> The best that I've found, when the function derivatives are
> continuous, is to make the contour at level=0 of the partial
> derivatives dz/dx and dz/dy, which effectively produce a nice
> "imprint" line BUT also contains some extra lines, corresponding to
> where one derivative is null but the other is not.
>
> So one could take both the zero contours of the two derivatives and
> say that the "imprint" line is the common curve among these two
> contours (don't really know how to do this in practice).
>
> In any case this does not work with not continuous derivatives, like
> my first example.
>
> How could I search if such an "imprint" function is available anywhere
> in the IDL library of somebody? Is there an IDL libraries database
> somewhere in the internet?

I tried this, and I at least get a circle:

IDL> TVScale, Sobel(z), /KEEP

I think something like that might work, with perhaps some thresholding,
etc.

Cheers,

David

--
David Fanning, Ph.D.
Coyote's Guide to IDL Programming (www.dfanning.com)
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Iso-contours at maximum/minimum levels By: Gianluca Li Causi on Thu, 29 January 2009 07:56
		Re: Iso-contours at maximum/minimum levels By: pgrigis on Mon, 02 February 2009 11:00
		Re: Iso-contours at maximum/minimum levels By: David Fanning on Mon, 02 February 2009 08:54

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