[Proj] Transverse or oblique width-aduusted Aitoff or Hammer-Aitoff for oblong regions.

Michael Ossipoff mikeo2106 at msn.com
Thu Jul 17 08:17:30 EDT 2008

When mapping an oblong or oval region, a region with unequal dimensions, a region that isn't close to being circular or square, and when linearity and conformality aren't needed, then why not use a transverse or oblique Aitoff or Aitoff-Hammer projection, centered in the mapped regiion?

Where Aitoff and Aitoff-Hammer multiply the azimuthal's X dimension by 2 (and change the grid the accordingly), here we multiply by a factor appropriate for the region's shape. If the region has one dimension 3.5 times its other dimension, then multiply by 3.5 instead of 2. Of course the projection's "equator" is along the region's long dimension, and the projection's center is at the center of the region.

The choice between Aitoff and Hammer-Aitoff would depend on whether or not equal-area is needed.

As I've said before, I suggest that, for general purpose maps of countries or states, equal area is a poor choice.

As I said when I proposed Apianus II, this obvious idea has probably been proposed before. If so, I'm proposing it again.

Mike Ossipoff

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