| Re: Image Map Overlays and Grids, Oh My! [message #64473] |
Mon, 05 January 2009 07:42 |
Jeremy Bailin
Messages: 618
Registered: April 2008
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Senior Member |
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On Jan 4, 9:59 pm, David Fanning <n...@dfanning.com> wrote:
> Folks,
>
> I typically spend the holidays slogging down eggnog,
> reading trashy novels, and working on an IDL project that
> has been bugging the daylights out of me because I don't
> have an extended period of time to work on it due to the
> usual pressures of job, family, tennis, etc.
>
> This year was no different. But what to do for a project?
>
> Since I've taken a real job, I spend an awful lot of time
> working with satellite images. It helps me a great deal
> when I am working with these images if I can see a few
> land masses in them in order to get my bearings, etc.
> And since these are generally map-projected images of
> some sort, I would like to be able to display map overlays
> of land boundaries, grid lines, etc.
>
> I have been absolutely chagrined at how few tools IDL
> has at it's disposal to do this kind of thing. Everything
> is clunky. Nothing is interactive. Probably iMap does
> what I want, but I honestly can't figure those damn iTools
> out and my blood pressure always rises into the danger level
> when I try to use them.
>
> I even tried to do this in ENVI, which I like for a lot
> of things, and especially for its flexible map projections.
> But following the recommended way to overlay a projected image
> with continental boundaries in ENVI resulted in a program that
> took about 3 minutes to display the image with its overlay!
> Uh, that is *way* too long, folks.
>
> So, long story short, I spent the holidays cobbling up
> a map coordinate object for my Catalyst Library that
> allows me to set up a map projection space in a very easy
> way. Then I wrote a couple of wrapper objects for Map_Continents
> (or Map_GSHHS_Shoreline, if you prefer that) and Map_Grid.
> Used with the map coordinate object, I can *automatically*
> get map overlays and grids on any georeferenced image.
>
> It's pretty sweet, if I do say so myself.
>
> You can see how I go about doing it in this article:
>
> http://www.dfanning.com/catalyst/maponimage.html
>
> This is the image display program I've always wanted. :-)
>
> Cheers,
>
> David
>
> P.S. Every time I look into map projections I get more frustrated
> with the map projection routines in IDL. Here is an area that could
> really use some of our maintenance dollars applied to it. Heck, how
> long could it take to move ENVI's map routines over to IDL? I am
> advising all my friends to completely avoid the MAP_SET routines.
> I no longer have any confidence in them. The MAP_PROJ_*** routines
> are better, but they are really limiting for someone who works with
> map projections on a daily basis. It wouldn't take a lot of work to
> do a LOT better in this area.
>
> --
> 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.")
Aha, now we have an easy way to test if David likes us. Ask him
whether to use the MAP_SET routines. If he says "no way!", you're in
his good books... if he says "go ahead!", watch out! ;-)
-Jeremy.
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