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Re: Need Some Good Ideas [message #29434 is a reply to message #29429]

Thu, 21 February 2002 08:09

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Ronn Kling (ronn@rlkling.com) writes:

> After you draw the contours around your blobs then create a blank pixmap of
> the same size as the image. (I am guessing that you are using device
> coordinates) Then draw the contour to the pixmap in a single color like 255.
> Do an im= TVRD() to get a new image and then do an indices = where( im eq
> 255). Turn these back to x,y coords and you have a very nearly evenly
> spaced series of points.

I've used this method before, and it might actually
work in this instance too, although it seems such
a hack I'm always embarrassed to have it in my
"professional" code. :-)

One of the problems with it, incidentally, is
that the points returned by the WHERE function
are not in the order you expect them to be in.
That is to say, the WHERE function doesn't find
one end of the line and proceed to the other end.
It can jump around, depending (I suppose) on how
the line is oriented on the image. We learned this
to our dismay when we were using this method to
calculate the length of line segments. We had
to add a routine to sort the WHERE indices into
a real line!

Cheers,

David
--
David W. Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438, E-mail: david@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155

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[Message index]

		Re: Need Some Good Ideas By: btupper on Thu, 21 February 2002 14:35
		Re: Need Some Good Ideas By: Martin Downing on Thu, 21 February 2002 14:35
		Re: Need Some Good Ideas By: David Fanning on Thu, 21 February 2002 11:22
		Re: Need Some Good Ideas By: btupper on Thu, 21 February 2002 10:43
		Re: Need Some Good Ideas By: David Fanning on Thu, 21 February 2002 08:09
		Re: Need Some Good Ideas By: David Fanning on Thu, 21 February 2002 07:50
		Re: Need Some Good Ideas By: dw on Thu, 21 February 2002 07:22
		Re: Need Some Good Ideas By: ronn on Thu, 21 February 2002 04:46
		Re: Need Some Good Ideas By: Craig Markwardt on Wed, 20 February 2002 23:46
		Re: Need Some Good Ideas By: Craig Markwardt on Wed, 20 February 2002 23:02
		Re: Need Some Good Ideas By: Stein Vidar Hagfors H[1] on Fri, 22 February 2002 09:05

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