Map projections and airborne moving map displays

The author discusses advantages and disadvantages of several methods of map projection, and identifies two methods that work well at any latitude with any map orientation. Four methods of map projection are discussed: cylindrical equidistant projection, sinusoidal projection, oblique orthographic projection, and oblique azimuthal equidistant projection. There are two modes of map displays, plan mode and map mode. Most of the discussion applies to the plan mode. For most applications, the projection of choice is orthographic projection. For maps of small areas with many target points, however, the cylindrical projection may be preferred due to computational requirements. For airborne maps with very long flight segments, the increased distance accuracy may make the azimuthal projections desirable. When properly implemented, the computational requirements of the orthographic and azimuthal projections are not significantly different