halfmap

A halfmap is a type of map projection that displays half of the Earth's surface. These projections are often used for specific purposes, such as illustrating hemispheres or visualizing data concentrated in one half of the globe. Unlike a full world map, a halfmap intentionally omits a significant portion of the planet.

The choice of which half to display can vary greatly depending on the intended application. For instance, a user might choose to show the Eastern Hemisphere or the Western Hemisphere, or a projection centered on a particular continent or ocean. The shape and distortion of landmasses and oceans will depend on the underlying projection method used to create the halfmap. Common projection types like Mercator, equirectangular, or azimuthal can be adapted to create halfmap views.

Halfmaps are useful in cartography and geographic information systems (GIS) when a comprehensive global view is not necessary or would be less effective for the data being presented. They can help to reduce visual clutter and highlight specific regions of interest. The concept is straightforward: take a standard map projection and clip it to show only half of the sphere.