| Re: Map projection of IMAGE() is behaving strangely... [message #86516 is a reply to message #86512] |
Fri, 15 November 2013 07:06   |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Andrew Smith writes:
> The longitude (x) coordinate appears to be mis-aligned so that the image pixels are stretched in that direction and the image area is filled by z[*,1:-1,*] instead of the full image z[*,*,*]. This doesn't happen in the latitude direction.
>
> Am I missing something fundamental about the MAP_PROJECTION property?
It seems to me the weirdness is not from the map projection, which I
think might actually be doing the *right* thing. I think the problem is
with the Image function. In this call:
;; Now add coordinates for bottom left point in each pixel.
im1 = IMAGE( z, lon, lat, $
AXIS_STYLE=2, $
TITLE='Add x/y coordinates', $
LAYOUT=[2,2,2], /CURRENT )
The image display shows coordinates that go from -60 to 60 in latitude,
and from -60 to 40 in longitude, but this isn't what is in the lat/lon
variables:
IDL> minmax, lat
MinMax: -60.0000 40.0000
IDL> minmax, lon
MinMax: -60.0000 20.0000
So, when you get to the map projection, you are getting the wrong
picture of what is suppose to be happening.
Don't know exactly. I just know something *always* seems to be weird
with function graphics routines when you look closely at them. ;-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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