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Re: read lambert projected image [message #88807 is a reply to message #88805] Sat, 21 June 2014 20:56 Go to previous message
David Fanning is currently offline  David Fanning
Messages: 11724
Registered: August 2001
Senior Member
audrey.schaufelberger@gmail.com writes:

> I see...
> Whereas the data used to produce the image is readily available from NASA, the image published is highly processed (cleaned, altitude-corrected, fitted, etc.). I only found one version of the image available (http://www.lpl.arizona.edu/~nic/Moon/LPMAG.html) and unfortunately I can't seem to locate the person who created this image to ask for the raw data. If I am not mistaken, the author neither mentions in this publication nor previous publications the
information you mention I need to know. All the author mentions is that an equal-area lambert projection was used... Lets say I would assume that she used a standard radius and a sphere as a Geoid, it would still be an immense task to transform the (x,y) corrdinates to (lon, lat) coordinate, right? I am wondering if it is even worth a try writing such a program from scratch...

No I don't think it will be an "immense" task. It might take 10-15
minutes if you understand map projections well enough to know what you
are doing. Learning about map projections might be an "immense" task,
depending on your definition. It took me 2-3 years, and I'm not always
100% sure I know what I'm doing now. In the scheme of things, that was
only 10% of the time I'm been working with IDL, so a short time. :-)

I've been moderately successful when "guessing" about map projections.
Knowing how to recompile and run IDL programs after making random
changes to the code helps. But, sometimes guessing doesn't work well at
all. Then, it is a lot of work for a null result.

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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