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.
World projections
Conformal | Mercator, Transverse, Oblique Mercator |
Equal Area | Cylindrical, Eckert IV, Eckert VI, Mollweide, Flat Polar Quartic, Sinusoidal |
Equidistant | Azimuthal |
Straight Rhumb Lines | Mercator |
Compromise | Miller, Robinson |
Hemisphere projections
Conformal | Stereographic, Polar |
Equal Area | Lambert Azimuth |
Equidistant | Azimuthal |
Global Look | Orthographic |
Continent or smaller region projections
Predominantly east–west along equator
Conformal | Mercator |
Equal Area | Cylindrical |
Predominantly east–west away from equator
Conformal | Lambert |
Equal Area | Albers |
Predominantly north–south
Conformal | Transverse, UTM |
Predominantly oblique
Conformal | Oblique Mercator |
Equal extent in all directions
Conformal | Polar, Stereographic, UPS |
Equal Area | Lambert Azimuth |
Straight Great-Circle Routes | Gnomonic |
Correct scale
Between Points | Two-Point Equidistant |
Along Meridians | Azimuthal (polar aspect), Equidistant, Equirectangular, Simple Conic |
Along Parallels | 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