| MAP_CONTINENTS procedure [message #7459] |
Tue, 19 November 1996 00:00  |
Wolfgang Knorr
Messages: 1
Registered: November 1996
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Junior Member |
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Hi,
supposedly, someone has already run into this problem, and possibly
it had already been discussed here, but I'd still like to post the
following question:
I want to display a global data on a map with the date line
in the center, using Mollweide's projection, and continental
boundaries. So I do:
map_set, /moll, /cont, /hor, 0, 180
The result is a little unsatisfactory, since IDL (at least my
Mac Version 4.0.1 does) connects lines accross the Greenwich
meridian right through my display. The best solution I could find:
map_set, /moll, /cont, /hor, 0, 180, limit = [-90, 0.5, 90, 359.5]
I do not find this very elegant, because I might miss out some data
points. Doing
map_set, /moll, /cont, /hor, 0, 180, limit = [-90, 0.1, 90, 359.9]
then has some problems similar to the first version.
My question: Does anyone know how to get around this problem?
Thanks a lot.
Wolfgang Knorr
Max-Planck-Institut fuer Meteorologie, Hamburg, GERMANY
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| Re: MAP_CONTINENTS procedure [message #7547 is a reply to message #7459] |
Wed, 20 November 1996 00:00  |
Andy Loughe
Messages: 174
Registered: November 1995
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Senior Member |
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Wolfgang Knorr wrote:
>
> Hi,
>
> supposedly, someone has already run into this problem, and possibly
> it had already been discussed here, but I'd still like to post the
> following question:
>
> I want to display a global data on a map with the date line
> in the center, using Mollweide's projection, and continental
> boundaries. So I do:
>
> map_set, /moll, /cont, /hor, 0, 180
>
> The result is a little unsatisfactory, since IDL (at least my
> Mac Version 4.0.1 does) connects lines accross the Greenwich
> meridian right through my display. The best solution I could find:
>
> map_set, /moll, /cont, /hor, 0, 180, limit = [-90, 0.5, 90, 359.5]
>
> I do not find this very elegant, because I might miss out some data
> points. Doing
>
> map_set, /moll, /cont, /hor, 0, 180, limit = [-90, 0.1, 90, 359.9]
>
> then has some problems similar to the first version.
> My question: Does anyone know how to get around this problem?
>
Don't get me started on map_set.
I rely on it and spend a great deal of my time creating "work arounds."
I don't use /cont when calling map_set, I use a home grown procedure
which contours the percentage of a grid box which is land. The
resolution
is .25 degrees by .25 degrees, and works for the mollweide projection.
I can make the source code and data set available to you if you wish.
And don't forget the /isotropic keyword!
You can specify a particular projection, but you won't get
a true projection of that type unless you specify /isotropic!
Figure that one out for me.
BTW: How does this look?
map_set, 0, 180, /cyl, limit=[-30,90,30,300], /cont, /iso
map_continents, /fill
Ok, I'll stop there.
> Thanks a lot.
>
> Wolfgang Knorr
> Max-Planck-Institut fuer Meteorologie, Hamburg, GERMANY
--
Andrew F. Loughe afl@cdc.noaa.gov
University of Colorado, CIRES http://cdc.noaa.gov/~afl
Campus Box 449 phn:(303)492-0707 fax:(303)497-7013
Boulder, CO 80309-0449 "He who laughs last thinks slowest!"
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