| Unproject Map Images [message #55416] |
Mon, 20 August 2007 09:34 |
mankoff
Messages: 131
Registered: March 2004
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Senior Member |
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Hi Group,
I have a bunch of images of Antarctica that I would like to unproject
from their (presumably spherical) projection so that I can add them as
layers to Google Earth. Google Earth requires that an overlay layer be
in cylindrical/equirectangular projection and the bottom edge must be
parallel to a latitude, in this case 90S. Your standard Antarctica
image looks like this: http://images.google.com/images?&q=antarctica+map
Ideally I want to write a procedure that takes the following
parameters:
1) (x,y) pixel location of 90S
2) radius (in pixels) to latitude 80S
3) Radius to latitude 70S
4) Rotation
I think with center and radius to a latitude you could 'unroll' or
unproject the map, but having two latitude radii would allow me to
verify the projection or determine if it is spherical or stereo or
something else. Perhaps. I guess this isn't really an unprojection so
much as a reprojection.
Anyway, on to my question: Has anyone done this? If not, does anyone
know of any tools that currently exist? And finally, if I code it in
IDL, do you suggest MAP_SET routines or MAP_PROJ routines. I do not
have any familiarity with the latter.
Thanks,
-k.
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