| Re: map_continents and /fill... revisted [message #76771] |
Sun, 03 July 2011 22:12 |
TonyL
Messages: 14
Registered: November 2008
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Junior Member |
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On Jul 2, 4:57 am, Brian McNoldy <brian.mcno...@gmail.com> wrote:
> On Jun 30, 2:48 am, Fabzou <fabien.mauss...@tu-berlin.de> wrote:
>
>> On 06/29/2011 09:46 PM, Brian McNoldy wrote:
>
>>> Other improvements on this topic would be updating political
>>> boundaries, including state-drawing options for at least Mexico and
>>> Canada, and allowing something like a map_ocean,/fill,color=blue.
>
>> I never used IDL mapping tools, but one can find also any kind of shapes
>> in various resolutions for almost anything for free in the Internet.
>> Often, political boundaries are necessary to create a readable map.
>
>> The obvious disadvantage is that you have to make the projection
>> transformations by yourself, and this can take some time.
>
> Thanks for the replies... I do not have 8.1, still on 8.0. Does
> anyone know offhand if the issue related to filling the larger islands
> is fixed by this new map database? I'm very happy to hear though that
> SOMETHING was addressed when it comes to the maps; there are certainly
> times that long rendering times are worth having an accurate end
> result.
I use IDL 8.1 in win7 (64bit) and found the GSHHS maps activated
using /hires in the map_continents command gives a reasonable map.
However I have tended to use the alternative gshhs_plot commands that
allow you to specify size of elements to be plotted, which level you
want etc.. (level 1 is continent, level 2 is water mass inside land,
level 3 is island inside water mass etc). Only time will tell if I
change.
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| Re: map_continents and /fill... revisted [message #76777 is a reply to message #76771] |
Fri, 01 July 2011 11:57  |
Brian McNoldy
Messages: 35
Registered: July 2000
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Member |
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On Jun 30, 2:48 am, Fabzou <fabien.mauss...@tu-berlin.de> wrote:
> On 06/29/2011 09:46 PM, Brian McNoldy wrote:
>
>> Other improvements on this topic would be updating political
>> boundaries, including state-drawing options for at least Mexico and
>> Canada, and allowing something like a map_ocean,/fill,color=blue.
>
> I never used IDL mapping tools, but one can find also any kind of shapes
> in various resolutions for almost anything for free in the Internet.
> Often, political boundaries are necessary to create a readable map.
>
> The obvious disadvantage is that you have to make the projection
> transformations by yourself, and this can take some time.
Thanks for the replies... I do not have 8.1, still on 8.0. Does
anyone know offhand if the issue related to filling the larger islands
is fixed by this new map database? I'm very happy to hear though that
SOMETHING was addressed when it comes to the maps; there are certainly
times that long rendering times are worth having an accurate end
result.
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| Re: map_continents and /fill... revisted [message #76794 is a reply to message #76777] |
Thu, 30 June 2011 01:48 |
Fabzou
Messages: 76
Registered: November 2010
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Member |
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On 06/29/2011 09:46 PM, Brian McNoldy wrote:
> Other improvements on this topic would be updating political
> boundaries, including state-drawing options for at least Mexico and
> Canada, and allowing something like a map_ocean,/fill,color=blue.
I never used IDL mapping tools, but one can find also any kind of shapes
in various resolutions for almost anything for free in the Internet.
Often, political boundaries are necessary to create a readable map.
The obvious disadvantage is that you have to make the projection
transformations by yourself, and this can take some time.
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| Re: map_continents and /fill... revisted [message #76798 is a reply to message #76794] |
Wed, 29 June 2011 20:11 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Michael Galloy writes:
> Do you have IDL 8.1? I don't use maps in IDL personally, but the release
> notes for IDL 8.1 says it improved the quality of the continental and
> country outlines.
IDL 8.1 does indeed allow the use of the GSHHS database,
which is generally thought to be one of the best in the
world for this kind of thing.
Unfortunately, the GSHHS software comes in several
"resolutions". IDL has included only the very highest
resolution, which you might think would be a good idea,
and probably is if your interest is in a rocky island
somewhere off the cost of Peru. If your interest is in
processing a map of the world, or even a reasonably
large portion of the world, then using the highest
resolution GSHHS is overkill in the extreme and will
result in VERY long rendering times. (And I mean long
even in terms of the normal function graphics rendering
times.)
It seems to me it still makes more sense to download
the GSHHS database yourself, and then use the resolution
that makes sense for your application. Coyote Library
routines are available to work with this database in
exactly the same way Map_Continents works with the
old IDL database.
http://www.idlcoyote.com/map_tips/gshhs.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 thue. ("Perhaps thos speakest truth.")
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| Re: map_continents and /fill... revisted [message #76801 is a reply to message #76798] |
Wed, 29 June 2011 14:09 |
Michael Galloy
Messages: 1114
Registered: April 2006
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Senior Member |
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On 6/29/11 1:46 PM, Brian McNoldy wrote:
> I realize this has been tossed around for at least 15 years on this
> list, but I'm wondering if any progress has been made or if anyone has
> a workaround. There are numerous instances where the maps that ship
> with IDL are quite inadequate... for example, if you try to fill the
> land with a color, you'll get most areas correct, but some bigger
> obvious places like Long Island, Trinidad, Grand Bahama Island,
> Kyushu, and the like are missed by the fill, and for routines that use
> such a technique to create a land/sea mask, this is definitely not
> good.
>
> Other improvements on this topic would be updating political
> boundaries, including state-drawing options for at least Mexico and
> Canada, and allowing something like a map_ocean,/fill,color=blue.
>
> Cheers,
> Brian
Do you have IDL 8.1? I don't use maps in IDL personally, but the release
notes for IDL 8.1 says it improved the quality of the continental and
country outlines.
Mike
--
Michael Galloy
www.michaelgalloy.com
Modern IDL, A Guide to Learning IDL: http://modernidl.idldev.com
Research Mathematician
Tech-X Corporation
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