| Re: map projections webinar [message #78058 is a reply to message #77920] |
Wed, 19 October 2011 00:33  |
David Fanning
Messages: 11724
Registered: August 2001
|
Senior Member |
|
|
Mark Piper writes:
> This Thursday, October 20, I'll be giving a set of webinars on using
map
> projection routines in IDL. For information and signup, please see
>
> http://www.ittvis.com/EventsTraining/LiveWebSeminars.aspx
>
> If you'd like to get my example programs beforehand, please follow this link
>
> http://bit.ly/IDL-webinar-files
>
> and look for "Using Map Projection Routines in IDL".
Because my sleep schedule is still a mess and I have no
idea what time or day it is, I decided to download these
webinar files and see if I could learn something. Mark
has written several programs to compare how you do various
map projection tasks in both direct graphics and in function
graphics.
Since Mark is making use of some Coyote Library routines
(albeit retired ones!) in his direct graphics examples, I
thought it might be interesting to write the same programs
from a Coyote Graphics point of view. Those of you who
have downloaded the Coyote Library may wish to compare and
contrast these routines with the routines Mark has written.
I've put the files here.
http://www.idlcoyote.com/misc/cg_map_projections.zip
They rely on software and data files that Mark is providing
for the webinar, so download his files first, then throw
the Coyote Graphics files in the same src directory as his
files. They are appropriately prepended with a "cg" extension
so you can tell them apart from Mark's files.
Each file is written as a simple display routine, which
can be displayed in a window or sent to a PostScript file,
etc. An example main-level program is at the end of all the
files, which will load the display routine into a resizeable
cgWindow, where you have access to PostScript and raster
output, as usual. If ImageMagick is installed, of course,
you have access to raster file output via PostScript
intermediate files and their extremely nice fonts.
Mark's files are probably not complete yet, but I noticed
one map projection task conspicuously missing. I would say
more than half the time when I am working with map projections
I have an image that has already been projected. What I want
to do is set up a map data coordinate space that is
coincident with the image, so I can draw continental
outlines, grid lines, station plots, etc. I am thinking,
for example, of any geoTiff image that I might download.
If Mark wanted to take this on for his webinar, here
is an appropriate image.
http://www.idlcoyote.com/misc/AF03sep15b.n16-VIg.tif.gz
I would be particularly interested in how to set up the
map data coordinate space for this image in function
graphics, for example. I've been able to create such
a coordinate system and display the image. But all goes
to hell when I resize the window. :-(
Here is an article that describes how to do such a thing
using Coyote Graphics:
http://www.idlcoyote.com/map_tips/tiffoverlay.html
If I wake up before noon, I may spend a little more time
on this tomorrow. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
