| Re: displaying an image in simple geographic coordinates [message #54152] |
Thu, 24 May 2007 23:48 |
Peter Albert
Messages: 3
Registered: April 2007
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Junior Member |
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I think you are mixing two things: the way in which your data is
defined (i.e. geographic coordinates, WGS84) and the way it is
displayed (i.e. projection). Nothing prevents you from displaying your
data in any projection you like. I guess, what you actually have in
mind is equirectangular, or plate carrée projection. This is actually
the default projection, so if you call map_set or the other projection
routines without any projection-related keyword, you should get what
you expect.
However, for your actual task of overplotting point data, you are not
restricted to this projection. With
plots, lonValues, latValues, pysm = 4, /data
after the projection, you should get the point data displayed
correctly regardless of the projection.
Regards,
Peter
On 25 Mai, 00:28, Matt <mmsmith1...@gmail.com> wrote:
> On May 24, 4:52 pm, David Fanning <n...@dfanning.com> wrote:
>
>
>
>> Matt writes:
>>> does anyone know how i can display an image in simple geographic
>>> coordinates using IDL? all documentation that i have read deals with
>>> reprojection images to various projections or reprojecting a window to
>>> a given image's projection. geographic coordinates is never listed as
>>> an option in any of these functions. maybe it's because i'm dealing
>>> with cartesian coordinates not a projected space per se? but my data
>>> is in lat/lon wgs84 and i need to plot point data that is in decimal
>>> degrees (wgs84) as well. any suggestions?
>
>> Here is an article that describes one way to do this:
>
>> http://www.dfanning.com/map_tips/precipmap.html
>
>> 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.")
>
> Thanks for the response. I checked out your link and it's very useful.
> It still leaves me with one question: it seems like you need to set up
> or initialize a projection before using map commands. what if your
> data is in geographic coordinates, which are not listed as a supported
> map structure? i suspect that there is something quite simple that i'm
> missing here. any thoughts?
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| Re: displaying an image in simple geographic coordinates [message #54159 is a reply to message #54152] |
Thu, 24 May 2007 15:28  |
Matt[1]
Messages: 23
Registered: December 2006
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Junior Member |
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On May 24, 4:52 pm, David Fanning <n...@dfanning.com> wrote:
> Matt writes:
>> does anyone know how i can display an image in simple geographic
>> coordinates using IDL? all documentation that i have read deals with
>> reprojection images to various projections or reprojecting a window to
>> a given image's projection. geographic coordinates is never listed as
>> an option in any of these functions. maybe it's because i'm dealing
>> with cartesian coordinates not a projected space per se? but my data
>> is in lat/lon wgs84 and i need to plot point data that is in decimal
>> degrees (wgs84) as well. any suggestions?
>
> Here is an article that describes one way to do this:
>
> http://www.dfanning.com/map_tips/precipmap.html
>
> 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.")
Thanks for the response. I checked out your link and it's very useful.
It still leaves me with one question: it seems like you need to set up
or initialize a projection before using map commands. what if your
data is in geographic coordinates, which are not listed as a supported
map structure? i suspect that there is something quite simple that i'm
missing here. any thoughts?
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| Re: displaying an image in simple geographic coordinates [message #54163 is a reply to message #54159] |
Thu, 24 May 2007 13:52 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Matt writes:
> does anyone know how i can display an image in simple geographic
> coordinates using IDL? all documentation that i have read deals with
> reprojection images to various projections or reprojecting a window to
> a given image's projection. geographic coordinates is never listed as
> an option in any of these functions. maybe it's because i'm dealing
> with cartesian coordinates not a projected space per se? but my data
> is in lat/lon wgs84 and i need to plot point data that is in decimal
> degrees (wgs84) as well. any suggestions?
Here is an article that describes one way to do this:
http://www.dfanning.com/map_tips/precipmap.html
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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