| Re: MAP_CONTINENTS with MAP_PROJ_INIT created !Map [message #63815 is a reply to message #63812] |
Wed, 19 November 2008 08:41  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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mike.otepka@gmail.com writes:
> Here's what I know how to do w.r.t. mapping continents onto an image
> (i.e. using MAP_SET):
>
> IDL> window,/f,xs=<xdim>,ys=<ydim>
> IDL> map_set,ctrlat,ctrlon,/projection_name,/noborder,/horiz, $
> xmargin=[0,0],ymargin=[0,0],limit=
> [latmin,lonmin,latmax,lonmax]
> IDL> tv, image
> IDL> map_continents
>
>
>
> Is there a way to do this using MAP_PROJ_INIT to create my !Map
> variable rather than MAP_SET?
> Here's what I've got so far:
>
> IDL> map = map_proj_init(projection_name, $
> limit=[latmin,lonmin,latmax,lonmax], $
> center_latitude =ctrlat, $
> center_longitude=ctrlon,
> $
> /GCTP)
>
> (Yeah, I know, not much.)
>
> According to IDL Help, MAP_PROJ_FORWARD or MAP_PROJ_INVERSE need to
> come into play but I don't really see how.
Oh, dear.
Well, I assume from this sketchy portrait that you have an image
that is already in a map projection, and you wish to associate
a map data coordinate system with it. Is that correct?
If so, you may be interested in this article, which will explain
how I use the MAP_PROJ* routines to do that:
http://www.dfanning.com/map_tips/precipmap.html
Of course, the method outlined in that article is not *exactly*
right, but it does point you (at the end of the article) to the
exact right solution. This is all going to be quite a bit more
complicated than what you are used to. Hope you are up for it. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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