| Extract Data from Point on Plot [message #64885] |
Thu, 29 January 2009 11:56  |
mrjejones
Messages: 3
Registered: January 2009
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Junior Member |
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I would like to be able to specify in coordinates (x,y) a point on my
plot and IDL tell me what latitude, longitude, and reflectivity (I am
using the Z device then read into PS for 2-D display) is plotted at
that point. Basically, I want the raw data for that specific plot
point. It must be command-line based.
Any help would be appreciated!
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| Re: Extract Data from Point on Plot [message #65007 is a reply to message #64885] |
Thu, 05 February 2009 13:32  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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mrjejones@gmail.com writes:
> I appreciate your help. I've read and use gobs of information from
> your website and turned the Coyote library documentation into a PDF
> (very handy). I'm going to read everything you said to but meanwhile I
> had found this procedure "MAP_PROJ_INVERSE". What you described is
> exactly what I want so I may ditch the map_proj.
Yes, MAP_PROJ_INVERSE and MAP_PROJ_FORWARD are your friends.
Just be *absolutely* sure you call MAP_PROJ_INIT each and
every time before you use them. That is to say, do NOT
rely on calling MAP_PROJ_INIT once and reusing the
map structure from that call in these other two routines.
The documentation will lead you to believe it works that
way, but it doesn't.
http://www.dfanning.com/map_tips/ephemeral.html
I use the MAPCOORD object in the Catalyst Library for these
sorts of projects. When I ask the MAPCOORD object for the
map structure (which I want to use, for example, in
MAP_PROJ_INVERSE) then it will automatically call
MAP_PROJ_INIT to create the map structure de novo.
Very handy.
> Thanks for all the assistance you give the IDL community.
You are very kind. Thank 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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