I've seen lots of world maps in the shape of two disks that touch, each one a separate projection of one hemisphere onto a disk -- usually the Western Hemisphere and the Eastern Hemisphere -- so together the full map covers the entire globe.

Is there a standard name for this kind of map projection onto 2 circular disks?

enter image description here from Wikipedia: Rumold Mercator

enter image description here from Wikipedia commons

Ideally I'd like a general name for all "2-disk" arrangements like this, but I'd be happy with separate specific names for "2 disks that use a Wulff net" and "2 disks that use a Schmidt net" and "2 disks that use a Mollweide map".

  • Nonperspective Azimuthal Projections progonos.com/furuti/MapProj/Normal/ProjAz/ProjAzNP/…
    – Mapperz
    Jan 22, 2013 at 21:52
  • 1
    Any projection of the sphere that maps a hemisphere into a disk can be made to work like this simply by mapping two complementary hemispheres and placing those maps side-to-side. Among such projections are the orthographic, stereographic, gnomonic, and azimuthal equidistant. Most azimuthal projections will map a hemisphere onto a disk. Perhaps that's why there is not a generic name for such two-disk maps AFAIK.
    – whuber
    Jan 22, 2013 at 23:14

1 Answer 1


A double hemisphere projection. Here's another example from 1691:

enter image description here

  • That's a nice illustration. However, the question does not ask for a specific name, but for a "general" name for all such world maps.
    – whuber
    Jan 22, 2013 at 23:15
  • 2
    @whuber Post edited to address comments. A "Double Hemisphere" projection is about as general as it gets--and according to the cartographer of the posted map, pretty accurate (i.e. Deux Plans-Hemispheres").
    – Aaron
    Jan 23, 2013 at 0:02

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