Conic Projections

ALBERS EQUAL-AREA CONIC

The Albers Equal-Area Conic projection is a map projection in which the parallels are unequally spaced arcs of concentric circles spaced closer to each other near the north and south edges of the map. The meridians are equally spaced and intersect the parallels at right angles.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:

Equal-area maps of regions with a predominantly east-west expanse, such as the United States, and valid for small extents or countries but not continents. It is used exclusively by the USGS for sectional maps of all 50 states.

 BELGIUM 72

The Belgium 72 Projection is a special case of the Lambert Conformal Conic (2-parallel) projection.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:
Maps of Belgium.

BIPOLAR OBLIQUE CONIC CONFORMAL

This conformal projection was constructed specifically for mapping North and South America. It is composed of two oblique adaptations of the Lambert Conformal Conic projection. The juncture of the two conic projections consists of a great circle arc cutting through Central America from southwest

to northeast. There is a slight mathematical discontinuity along this arc, which is resolved by an adjustment that leaves a small intermediate area slightly non-conformal. The Earth is treated as a sphere by this projection, due to the relatively small scale of the map.

The Bipolar Oblique Conformal Conic projection has no parameters, as the poles and parallels used by the conic projections are set to specific values.

Usage:
Maps of North and South America together

BONNE

The Bonne projection is pseudoconical and equal-area. The central meridian is a straight line. Other meridians are complex curves. Parallels are concentric circular arcs, but the poles are points. Scale is true along the central meridian and along all parallels. There is no distortion along the central meridian and along the standard parallel.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of standard parallel

Usage:
Atlas maps of continents and topographic mapping in some countries.

Notes:
In this projection, a world map has a heart shape.

EQUIDISTANT CONIC

The Equidistant Conic is the simplest kind of conic projection. It is the projection most likely to be found in atlases of small countries, with its equally spaced straight meridians and equally spaced circular parallels.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:
Atlases of small countries.

GUAM 27

Important Notes:

NOT FOR CARTOGRAPHIC USE. Use only to import legacy data that might have been saved in this system and then transform to a new coordinate system

Information:

The State Plane Coordinate System (SPCS) is not a projection; rather it is a system for specifying positions of geodetic stations using plane rectangular coordinates. This coordinate system divides all fifty states of the United States, Puerto Rico and the U.S. Virgin Islands into over 120 numbered sections, referred to as zones. Each zone has an assigned code number that defines the projection parameters for the region.

There are four possible projections for SPCS. The geometric direction of each state determines the projection utilized. For states that are longer in the east-west direction, the Lambert Conformal Conic is used. States which are longer in the north-south direction use the Transverse Mercator projection. The panhandle of Alaska, which has the sole distinction of lying at an angle, garners the use of the Oblique Mercator projection, while Guam uses a Polyconic projection

The formulae for these calculations are based on Publication 62-4, "State Plane Coordinates by Automatic Data Processing", U.S. Department of Commerce 1968. These projections should only be used for data that has been computed using this method. For all other state plane calculations use Exact Methods. The parameters for these coordinate systems are defined in Publication 62-4. For further information contact the U.S. Department of Commerce.

The Guam27 projection does not require any parameters.

IMW POLYCONIC

The IMW Polyconic projection is a modified Polyconic projection devised as a basis for the 1:1,000,000-scale International Map of the World (IMW) series. The IMW Polyconic projection differs from the ordinary Polyconic in two principle ways. All meridians are straight and two meridians are made true to scale.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:
Very large scale maps are part of the IMW series.

Notes:
Only valid about 8-10 degree from central meridian and latitude of origin.

KROVAK

Important Notes:

NOT FOR RECOMMENDED CARTOGRAPHIC USE. This projection uses Westing and Southing instead of the regular Easting and Northing value; maps created in this system in Adobe Illustrator would look flipped in north/south and east/west directions. Use this projection only to import source data in this system and then transform to a different choice, or for export.

Information:

The Krovak Projection was created and used in former Czechoslovakia in the early part of the 20th century. It is an oblique version of the Lambert Conformal Conic projections with a pseudo standard parallel that intersects the centerline of the projection at a defined azimuth. The projection accurately preserves scale and area along the pseudo standard parallel. It is primarily used in the Czech Republic.

Parameters:

azimuth	Azimuth
central_meridian	Origin longitude (centerline)
false_easting	False easting
false_northing	False northing
latitude_of_origin	Origin latitude
latitude_of_true_scale	Latitude of true scale
scale_factor	Scale reduction factor at the centre of the projection
x_scale	Scale reduction on the X axis (default is 1)
xy_plane_rotation	XY plane rotation (optional, default is 0).
y_scale	Scale reduction on the Y axis (default is 1)

Usage:
Maps of Czech Republic or Slovakia.

LAMBERT CONFORMAL CONIC (2 PARALLELS)

The Lambert Conformal Conic (2 parallel) projection is a map projection in which the scale is true along two standard parallels, and the true shape of small areas is preserved. Parallels are unequally spaced arcs of concentric circles spaced closer to each other near the centre of the map. The meridians are equally spaced and intersect the parallels at right angles. The scale is true along two standard parallels.

Parameters:

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:

Widely used in atlases, in aeronautical charts, and in plane coordinate systems in surveying. It is also used in the US State Plane Coordinate System for states with large east-west extents.

LAMBERT TANGENT

The Lambert Tangent or Lambert Conformal Conic (1 parallel) projection is a map projection in which the scale is true along a single standard parallel, and the true shape of small areas is preserved. Parallels are unequally spaced arcs of concentric circles spaced closer to each other near the centre of the map. The meridians are equally spaced and intersect the parallels at right angles.

Parameters: 

central_meridian	Longitude of the centre of the projection
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
scale_factor	Scale reduction factor at the centre of the projection

Usage:
Used extensively in France.

LAMBERT CONFORMAL CONIC EXTENDED

This is a variation of the standard Lambert Conformal Conic projection that is provided for the definition of coordinate systems used in specific counties in the U.S. states of Minnesota and Wisconsin. Within a specific county in one of these states, the ellipsoid must be expanded by an additional amount to account for the average elevation within that county. In the case of a Wisconsin county, the ellipsoid must also be adjusted based on the average geoid height for that county. For Minnesota counties, the average geoid height should be set to zero.

Parameters:

Minnesota
average_elevation	Average elevation (Minnesota and Wisconsin)
average_geoid_height	Average geoid height (Wisconsin-only)	0
central_meridian	Longitude of origin
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
scale_factor	Scale reduction factor at the centre of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:
County maps of Minnesota and Wisconsin.

LAMBERT 27

Important Notes:

NOT FOR CARTOGRAPHIC USE. Use only to import legacy data that might have been saved in this system and then transform to a new coordinate system

Information:
The Lambert State Plane 27 is part of the State Plane Coordinate System (SPCS). See Guam27 for more information.

The Lambert 27 projection does not require any parameters.

PERSPECTIVE CONIC

The Perspective Conic projection is produced by projecting the Earth perspectively from the centre (or from some other point) onto a tangent or secant cone, along the standard parallels. The meridians are equally spaced straight lines converging at a common point representing one of the poles. The parallels are represented as unequally spaced concentric circular arcs centered on the pole of convergence of the meridians. The other pole may not be represented on the projection, though in some cases it may appear as a circular arc.

Parameters: 

central_meridian	Longitude of the central meridian
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection
standard_parallel1	Latitude of southern standard parallel
standard_parallel2	Latitude of northern standard parallel

Usage:
Aesthetical maps of Earth.

Notes:

Should not be used on non-hemispherical area — requires crop before transforming. Quick distorsions appear away from standard latitudes and central meridians. Only a spherical form is supported (using semi-major axis of ellipsoid)

POLYCONIC

The Polyconic projection is neither an equal-area nor a conformal projection. Scale is true along each parallel and along the central meridian. Parallels of latitude are arcs of non-concentric circles and the projection is free of distortion only along the central meridian.

Parameters:

central_meridian	Longitude of the centre of the projection
false_easting	False easting
false_northing	False northing
latitude_of_origin	Latitude of origin of the projection

Usage:

This projection can be used to represent small areas on any part of the globe, preserving shapes, areas, distances, and azimuths in their true relation to the surface of the earth. Polyconic projections over large areas usually result in serious errors and exaggeration of details. Used in USGS 7.5 and 15 minutes quad sheets.