[OSRS-PROJ] Quadrilatieralized Spherical Cube projection
Clifford J Mugnier
cjmce at lsu.edu
Fri Apr 2 08:45:16 EST 2004
I think Oscar S. Adams worked up a conformal projection of the sphere onto
a cube in the 1920s or 1930s. Lee addressed it in his monograph on
Conformal Projections of the Ellipsoid in Cartographia (I think), and John
P. Snyder (of course) wrote of it since Elassal's GCTP was his translation
of Snyder into Fortran. Gnomonic is certainly the simplest way to do it,
but a conformal projection would really be the only approach to a "low
distortion" solution. The implementation is non-trivial.
Cliff Mugnier
LOUISIANA STATE UNIVERSITY
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I need to efficiently (with low distortion) divide the globe into
square tiles in order to store global images. I am currently using a
modified gnomonic projection onto a cube. The projection I am
currently using is an arctangent of the gnomonic projection (which
could also be visualized as two cylindrical projections, one for each
axis). I am using a modified version of GCTP for this, but Proj.4
looks a lot better. There doesn't seem to be any existing projection
similar to what I am using, but in the course of my research I found
out about the Quadrilatieralized Spherical Cube projection, which
sounds a lot better.
This projection is used by the COBE project to store images of the sky.
It is a projection of the sphere onto a cube and is supposed to have
distortion of less than 1%.
It looks like the Quadrilatieralized Spherical Cube projection doesn't
currently exist in Proj.4, but if needed I am willing to add it. My
question is: does this projection already exist under a different name,
or is there something else that can be used? If I add this projection,
could it be included with the main distribution?
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