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Re: Edge detection and convert edges into polygons [message #61916 is a reply to message #61899]

Fri, 01 August 2008 08:11

pgrigis
Messages: 436
Registered: September 2007

Senior Member

M. Suklitsch wrote:
> Hi!
>
>
> I need some hint on how to convert edges into vertices. What I want to
> do in the end is check whether a station (of which I have lon/lat
> values) lies within such a vertex.
>
> To be more precise: I have a netCDF file with three fields. longitude,
> latitude and mask, where mask has integer values and defines
> subregions. In this mask "image" I want to detect the edges, what I
> already got working using the tips on http://www.dfanning.com/ip_tips/sharpen.html.
>
> These edges I want to convert into vertices which I then put in an
> IDLanROI object. Using this object I could then very easily check if a
> station given by its longitude and latitude lies within a region or
> not.

Still not sure if I understand... do you have a mask wich is built out
of several disconnected pieces and you are trying find out, for a
given
point, in which part of the mask it lies?

Ciao,
Paolo

>
>
> Another possibility would be to simply search the nearest gridpoint to
> my station and say that the region index of this gridpoint is the one
> for my station. But I think the first way is more correct. Does anyone
> have some idea on how to do this? I hope I explained the problem in a
> way that everybody understands it. :)
>
>
> Thanks in advance!
>
> Cheers,
> Martin

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[Message index]

		Re: Edge detection and convert edges into polygons By: M. Suklitsch on Mon, 04 August 2008 00:50
		Re: Edge detection and convert edges into polygons By: pgrigis on Fri, 01 August 2008 08:11
		Re: Edge detection and convert edges into polygons By: David Fanning on Fri, 01 August 2008 08:06

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