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Re: Contouring data over maps [message #12433]

Wed, 05 August 1998 00:00

wmc
Messages: 117
Registered: February 1995

Senior Member

<35C7589E.C37A0F1C@rex.cs.tulane.edu>, hasenbuh@rex.cs.tulane.edu wrote:
> Here's a worst case, maybe it can explain my problem:
> ...\##/...
> ....\/....
> ..*.||.*..
> ..../\....
> .../##\...
>
> My data points are at the asterisks. With the
> current method the data that is extrapolated from my
> data by IDL will be heavily influenced by BOTH data
> points, where, if I could find some way to respect the
> coastlines, I would expect IDL to consider these points
> much farther away than their cartesian distance.

Hmmm, I see your problem, for which my previous solution is no help at all.
Bascially you want a "real" GIS package for this kind of stuff, one that
allows you to specify "fault lines", which in your case would be the coast
line. I'm fairly sure that geologists do this stuff all the time.

To fake this in IDL would probably be tricky. Possibly you could add fake
points along the coast, use triangulate to define your triangulation, do some
reordering of this triangulation, and then use trigrid to interpolate. But
"do some reordering" would be the tricky bit. Perhaps
at that stage you could just delete any triangles that use the fake coastal
points?

- William

---
William M Connolley | wmc@bas.ac.uk | http://www.nbs.ac.uk/public/icd/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself,
and in this particular case have a fair old chance of burbling rubbish!

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[Message index]

		Re: Contouring data over maps By: wmc on Wed, 05 August 1998 00:00
		Re: Contouring data over maps By: Jason Hasenbuhler on Wed, 05 August 1998 00:00
		Re: Contouring data over maps By: rjh55 on Wed, 05 August 1998 00:00
		Re: Contouring data over maps By: rmlongfield on Wed, 05 August 1998 00:00
		Re: Contouring data over maps By: Jason Hasenbuhler on Tue, 04 August 1998 00:00
		Re: Contouring data over maps By: wmc on Tue, 04 August 1998 00:00
		Re: Contouring data over maps By: davidf on Mon, 03 August 1998 00:00

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