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.
> 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.
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.
-- 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.")
> 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.
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.
> 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.
