When choosing a projection in which to store your database, consider the database's primary use.
- Databases created under contract or to be used by a government organization are often in a projection determined by the governing body, such as state plane in the United States or Great Britain National Grid in the United Kingdom.
- Use equal area projections for thematic or distribution maps.
- Presentation maps are usually conformal projections, although compromise and equal area projections can also be used.
- Navigational maps are usually Mercator, true direction, and/or equidistant.
Other considerations for map projection choice
- The extent of the area to be mapped. Is it a database of the world, a continent, or a state?
- Location of the area to be mapped. Is it a polar, midlatitude, or equatorial region?
- Predominant extent of the area to be mapped. Is the area roughly circular or longer in the east–west, north–south, or some oblique direction?
The list below shows a range of choices for common map types.
Mercator, Transverse, Oblique Mercator
Cylindrical, Eckert IV, Eckert VI, Mollweide, Flat Polar Quartic, Sinusoidal
Straight Rhumb Lines
Continent or smaller region projections
Predominantly east–west along equator
Predominantly east–west away from equator
Equal extent in all directions
Polar, Stereographic, UPS
Straight Great-Circle Routes
Azimuthal (polar aspect), Equidistant, Equirectangular, Simple Conic
Polyconic, Sinusoidal, Bonne
These tables are based on Snyder, John P., 1987, Map Projections, A Working Manual, U.S. Geological Survey Professional Paper 1395, 385p.http://pubs.er.usgs.gov/publication/pp1395