| Re: Display of topo map in MAP routines. [message #68037] |
Tue, 22 September 2009 13:56 |
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Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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Kenneth P. Bowman wrote:
> In article <h9b1dm$kse$1@news.woc.noaa.gov>,
> Paul van Delst <paul.vandelst@noaa.gov> wrote:
>
>> Hello,
>>
>> I'm sure this question has come up before (I did a quick search of David Fanning's tips
>> but didn't immediately see anything). Apologies in advance for being a bit lazy....
>>
>> Can someone outline (real quick) the steps needed to display a topo map in the background
>> of a map projection? Other point data will be overplotted over this background.
>>
>> Does a DEM file come with IDL, or do I need to visit the USGS?
>>
>> Thanks for any info/help.
>>
>> cheers,
>>
>> paulv
>
> If you go to my downloads page
>
> http://idl.tamu.edu/Downloads.html
>
> and download my library
>
> http://csrp.tamu.edu/downloads/idl/bowman_lib.zip
>
> it includes some routines to read your choice of two different
> global topography databases. (They are included in the download.)
>
> These data are on 5-minute and 10-minute lat-lon grids, and may
> not have the resolution that you need.
>
> There is also a land-ocean data base with associated access routines.
>
> Plot the maps and then fire away with PLOTS.
Excellent, thanks!
cheers,
paulv
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| Re: Display of topo map in MAP routines. [message #68038 is a reply to message #68037] |
Tue, 22 September 2009 13:41  |
Kenneth P. Bowman
Messages: 585
Registered: May 2000
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Senior Member |
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In article <h9b1dm$kse$1@news.woc.noaa.gov>,
Paul van Delst <paul.vandelst@noaa.gov> wrote:
> Hello,
>
> I'm sure this question has come up before (I did a quick search of David Fanning's tips
> but didn't immediately see anything). Apologies in advance for being a bit lazy....
>
> Can someone outline (real quick) the steps needed to display a topo map in the background
> of a map projection? Other point data will be overplotted over this background.
>
> Does a DEM file come with IDL, or do I need to visit the USGS?
>
> Thanks for any info/help.
>
> cheers,
>
> paulv
If you go to my downloads page
http://idl.tamu.edu/Downloads.html
and download my library
http://csrp.tamu.edu/downloads/idl/bowman_lib.zip
it includes some routines to read your choice of two different
global topography databases. (They are included in the download.)
These data are on 5-minute and 10-minute lat-lon grids, and may
not have the resolution that you need.
There is also a land-ocean data base with associated access routines.
Plot the maps and then fire away with PLOTS.
Cheers, Ken Bowman
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| Re: Display of topo map in MAP routines. [message #68039 is a reply to message #68038] |
Tue, 22 September 2009 13:39 |
Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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David Fanning wrote:
> Paul van Delst writes:
>
>> Can someone outline (real quick) the steps needed to display a topo map in the background
>> of a map projection? Other point data will be overplotted over this background.
>
> Do you really mean "topo map"? If you do, I'm not sure
> there *is* a quick way to do this. Maybe if you could
> get ahold of a digital topo map in GeoTIFF format you
> might be OK. But even the smallest topo map is going to
> be HUGE and difficult to work with. I have a topo map of
> Canyonlands National Park in front of me on the wall.
> It's about 3 by 4 feet. I hate to think what size it would
> be in digital format. :-(
>
>> Does a DEM file come with IDL, or do I need to visit the USGS?
>
> IDL does not come with a DEM file. Is this what you
> mean by a "topo map"?
>
> Maybe you could clarify what you are trying to do,
> including some explanation of the tools you plan to
> use. I have a feeling you are asking about building
> a 18,000 sq ft dream home, but have the plans for a
> dog house in front of you. :-)
If I grok the analogy correctly, I think I mean the opposite. I'll be quite happy with the
doghouse version. :o)
But I did mean a digital elevation map (i.e. lat, lon, height). A colleague supplied the
GTOPO30 DEM data from the USGS and I bumbled my way through to actually displaying the
elevation data on a map (yay!).
I was trying to avoid the hassle of writing code to read the DEM file - but it ended up
being relatively simple. Once I have x, y, and z data in IDL I can figure out how to
display stuff by browsing your site and my books -- it was getting said data from disk
file to IDL variable that I was being lazy about. I thought there was some well know-about
file with an object reader in IDL (at least, to the DEM/IDL cognoscenti) but I guess not.
Sorry for the newsgroup noise...
cheers,
paulv
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| Re: Display of topo map in MAP routines. [message #68040 is a reply to message #68039] |
Tue, 22 September 2009 12:22 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Paul van Delst writes:
> Can someone outline (real quick) the steps needed to display a topo map in the background
> of a map projection? Other point data will be overplotted over this background.
Do you really mean "topo map"? If you do, I'm not sure
there *is* a quick way to do this. Maybe if you could
get ahold of a digital topo map in GeoTIFF format you
might be OK. But even the smallest topo map is going to
be HUGE and difficult to work with. I have a topo map of
Canyonlands National Park in front of me on the wall.
It's about 3 by 4 feet. I hate to think what size it would
be in digital format. :-(
> Does a DEM file come with IDL, or do I need to visit the USGS?
IDL does not come with a DEM file. Is this what you
mean by a "topo map"?
Maybe you could clarify what you are trying to do,
including some explanation of the tools you plan to
use. I have a feeling you are asking about building
a 18,000 sq ft dream home, but have the plans for a
dog house in front of you. :-)
Cheers,
David
--
David Fanning, Ph.D.
Coyote's Guide to IDL Programming (www.dfanning.com)
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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