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Re: Edge detection for saturn's rings [message #61390 is a reply to message #61345]

Wed, 16 July 2008 07:02

Vince Hradil
Messages: 574
Registered: December 1999

Senior Member

On Jul 15, 10:02 pm, David Fanning <n...@dfanning.com> wrote:
> frankosuna writes:
>> I've been trying to use some of the built in edge detection routines
>> implemented in idl such as sobel but I haven't found a very good one
>> that will work for images such as this:
>
>> http://frankosuna.googlepages.com/supportImage.jpg
>
>> I am trying to pull out all of the rings in this image and the best I
>> have gotten is this:
>
>> http://frankosuna.googlepages.com/edgeDetect.jpg
>
>> Any suggestions and opinions are welcome.
>
> Andrew Cool points out to me that as a backyard astronomer, he
> is always interested in this kind of thing, and that the CANNY
> edge detection routine is often the best one for this kind of
> separation. Oddly, though, there is no mention of the CANNY
> routine under "Edge Detection" in either the IDL 6.4 or IDL 7.x
> on-line help! An oversite we hope someone at ITTVIS notices.
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

I dug around a couple of years ago and found a canny implementation in
idl. I fixed it up so that it works pretty well for me, but I haven't
used it in quite a while. The header mentions Julian Walmsley, 1999
requires IDL 5.2.x - based on Gideon Amos, 1997, requires IDL 4.x.

Cheers,
Vince

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[Message index]

		Edge detection for saturn's rings By: frankosuna on Mon, 14 July 2008 17:43
		Re: Edge detection for saturn's rings By: frankosuna on Wed, 16 July 2008 09:10
		Re: Edge detection for saturn's rings By: David Fanning on Wed, 16 July 2008 07:06
		Re: Edge detection for saturn's rings By: Vince Hradil on Wed, 16 July 2008 07:02
		Re: Edge detection for saturn's rings By: David Fanning on Tue, 15 July 2008 20:02

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