| Re: Filling in the Gaps (contour mapping) [message #20037] |
Thu, 11 May 2000 00:00 |
wmc
Messages: 117
Registered: February 1995
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Senior Member |
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Simon de Vet <simon@mathstat.dal.ca> wrote:
> When plotted, the vast majority looks great. However, at the seam
> running through 0 longitude, the two edges are not connected...
Thwe answer, as I recall (and it may even be in the doc, not sure) is
that you need to define "wrap around" points, ie
0, 3.75, 2*3.75,...,360-3.75, [360]
where the extra [360] point is given the same value as 0 (of course).
-W.
--
William M Connolley | wmc@bas.ac.uk | http://www.nbs.ac.uk/icd/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
(yes, BAS has at at last got rid of that irritating "public" in the URL)
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| Re: Filling in the Gaps (contour mapping) [message #20040 is a reply to message #20037] |
Thu, 11 May 2000 00:00  |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Simon de Vet (simon@mathstat.dal.ca) writes:
> I am a new user to IDL (day 4 and having fun, now that I have some stuff
> working), so please forgive me if this is an obvious question.
>
> I have data that I am contour plotting onto a world map. The data is
> spaced every 3.75 degrees in latitude and longitude. The longitude
> starts at 0 and ends at 356.25. Latitude runs from -88.125 to 88.125.
>
> When plotted, the vast majority looks great. However, at the seam
> running through 0 longitude, the two edges are not connected. While it
> is less obvious, I assume that a similar problem is occuring at the
> poles. The poles are not much of a concern, since the top 10 degrees are
> cut off in a Mercator projection anyways...
>
> Since the data does not connect, I cannot use a filled contour plot,
> which is one of my goals.
>
> Any suggestions? Is there an easy way to do this, or will I have to have
> the first longitudinal values repeated at the end of the list? It seems
> that IDL is not recognizing that 0 degrees and 360 degrees are the same
> thing.
Humm. I don't see any disconnect when I do this with or without
contour filling. Better let us have a peak at this part of
your code. :-)
And if you are doing filled contours, you better have a look
at my web page before you get too much further along. There
are a couple of things there you might need that you won't
find in your IDL documentation. :-)
I'd start with this one, but there are a couple you should look
at:
http://www.dfanning.com/tips/contour_hole.html
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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