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Re: Contouring data over maps [message #12454 is a reply to message #12453]

Tue, 04 August 1998 00:00

wmc
Messages: 117
Registered: February 1995

Senior Member

102ff455a31f815f989824@news.frii.com, davidf@dfanning.com (David Fanning) writes:
> Jason Hasenbuhler (hasenbuh@rex.cs.tulane.edu) writes:
>
>> What I need to know is how to make IDL respect the land/sea continental
>> boundries when I plot my interpolated data.
>
> There is, I feel safe in saying, no easy way to do what you want to do.

I think Davids right. I have found in the past that attempting to define "nodata"
regions with contour causes problems at the edges of those regions. It has been
easier to contour everywhere, and then polyfill in white/background everywhere
else (and then redraw the coastline, probably, because bits of it will have
been clipped).

Unfortunately, map_continents does not appear to have an option to fill the sea
regions. I'd do it by using a GCM land-sea mask but you probably don't have that.
If you're drawing to the screen, then:

set your map projection
map_continents,/fil
mask=tvrd()
contour your data
img=tvrd()
img(where(mask eq !p.background))=!p.background
tv,img

ought to work. Some variant might work with postscript, too.

---
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

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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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