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Re: fitting contours with ellipse [message #69338]

Tue, 05 January 2010 07:55

fburton
Messages: 19
Registered: June 2003

Junior Member

In article <MPG.25ace65126e824569896c7@news.giganews.com>,
David Fanning <news@dfanning.com> wrote:
> Alas, the problem with the contours that come from
> the contour command is that some of the time they
> are NOT "well spaced". In fact, they are vectors.
> So, if a contour segment is straight (say along an edge)
> there will be no points at all between the ends
> of the straight segment.

Good point - but for a complete set of edge points to fit
an ellipse well would require it to be exceedingly eccentric.
A likely alternative is that part of the ellipse lies outside
the contoured area, in which case not having any points along
the straight edge would give a better fit.

> It was to get around this problem (among others) that
> I wrote ArcSample, which samples a closed curve at
> approximately equal intervals. It essentially
> digitizes a contour line so you can do something
> useful with it later. (I used it in my ActiveContour
> program.)
>
> http://www.dfanning.com/programs/arcsample.pro

That's neat!

Francis

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[Message index]

		Re: fitting contours with ellipse By: fburton on Tue, 05 January 2010 07:55
		Re: fitting contours with ellipse By: David Fanning on Tue, 05 January 2010 05:02
		Re: fitting contours with ellipse By: fburton on Tue, 05 January 2010 03:22
		Re: fitting contours with ellipse By: natha on Fri, 08 January 2010 10:24

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