| Description: The map_projection_name attribute provides the name of the map projection. Definitions when available are from Synder, J.P., 1987, Map Projections: A Working Manual, USGS Numbered Series, Professional Paper 1395, URL: https://doi.org/10.3133/pp1395. |
| Namespace Id: cart | Steward: img | Class Name: Map_Projection | Type: ASCII_Short_String_Collapsed |
| Minimum Value: None | Maximum Value: None | Minimum Characters: 1 | Maximum Characters: 255 |
| Unit of Measure Type: None | Default Unit Id: None | Attribute Concept: None | Conceptual Domain: SHORT_STRING |
| Status: Active | Nillable: false | Pattern: None |
| Permissible Value(s) | Value | Value Meaning |
| | Albers Conical Equal Area | Projection is mathematically based on a cone that is conceptually secant on two parallels. No areal deformation. North or South Pole is represented by an arc. Retains its properties at various scales; individual maps can be joined along their edges. |
| | Azimuthal Equidistant | Projection is mathematically based on a plane tangent to the body. The entire body can be represented. Generally the Azimuthal Equidistant map projection portrays less than one hemisphere, though the other hemisphere can be portrayed but is much distorted. Has true direction and true distance scaling from the point of tangency. |
| | Equidistant Conic | Projection is mathematically based on a cone that is tangent at one parallel or conceptually secant at two parallels. North or South Pole is represented by an arc. |
| | Equirectangular | Also called Equidistant Cylindrical, this projection is neither equal-area or conformal and is known for its very simple construction. Equations only allow spherical body definitions. The meridians and parallels are all equidistant straight parallel lines, intersecting at right angles. If the Equator is made the standard parallel, true to scale and free of distortion, the meridians are spaced at the same distances as the parallels, and the graticule appears square. In this formation, when the Equator is made the standard parallel, this projection is also known as Plate Carree or the Simple Cylindrical projection. |
| | Gnomonic | This projection is geometrically projected onto a plane, and the point of projection is at the center of the body. It is impossible to show a full hemisphere with one Gnomonic map. It is the only projection in which any straight line is a great circle, and it is the only projection that shows the shortest distance between any two points as a straight line. |
| | Lambert Azimuthal Equal Area | The Lambert Azimuthal Equal-Area projection is mathematically based on a plane tangent to the body. It is the only projection that can accurately represent both areas and true direction from the center of the projection. This projection generally represents only one hemisphere. |
| | Lambert Conformal Conic | Projection is mathematically based on a cone that is tangent at one parallel or (more often) that is conceptually secant on two parallels. Areal distortion is minimal but increases away from the standard parallels. North or South Pole is represented by a point; the other pole cannot be shown. Great circle lines are approximately straight. It retains its properties at various scale and maps can be joined along their edges. |
| | Mercator | Projection can be thought of as being mathematically based on a cylinder tangent at the equator. Any straight line is a constant-azimuth (rhumb) line. Areal enlargement is extreme away from the equator; poles cannot be represented. Shape is true only within any small area. Reasonably accurate projection within a 15 degree band along the line of tangency. |
| | Miller Cylindrical | Similar to Mercator, this projection is neither equal-area or conformal. Equations only allow spherical body definitions. The meridians and parallels are straight lines, intersecting at right angles. Meridians are equidistant and parallels are spaced farther apart away from Equator. Generally used for global maps. |
| | Oblique Cylindrical | This projection works by moving the north pole of the simple cylindrical projection. The pole latitude and longitude are the location of the new north pole, and the rotation is the equivalent to the center longitude in simple cylindrical. Because of the supported rotation parameter, this projection is pretty uniquely used in the planetary community and it is implemented in USGS's Integrated Software for Imagers and Spectrometers v2/3 (ISIS3) suite. |
| | Oblique Mercator | The projection is mathematically based on a cylinder tangent along any great circle other than the equator or a meridian. Shape is true only within any small area. Areal enlargement increases away from the line of tangency. Reasonably accurate projection within a 15 degree band along the line of tangency. |
| | Orthographic | The Orthographic projection is geometrically based on a plane tangent to the body, and the point of projection is at infinity. The body appears as it would from outer space. This projection is a truly graphic representation of the body and is a projection in which distortion becomes a visual aid. It is the most familiar of the azimuthal map projections. Directions from the center of the Orthographic map projection are true. |
| | Point Perspective | Similar to Orthographic, this projection is often used to show the body as seen from space. This appears to be the same as the Vertical Perspective projection as define in Synder, J.P., 1987, Map Projections: A Working Manual. Vertical Perspective projections are azimuthal. Central meridian and a particular parallel (if shown) are straight lines. Other meridians and parallels are usually arcs of circles or ellipses, but some may be parabolas or hyperbolas. This is neither conformal or equal-area. |
| | Polar Stereographic | Related to the Stereographic projection but generally centered directly at the North or South Pole of the body (e.g. latitude_of_projection_origin set at 90 or -90 respectively). This resembles other polar azimuthals, with straight radiating meridians and concentric circles for parallels. The parallels are spaced at increasingly wide distances the farther the latitude is from the pole. Note, if you do supply the optional attribute scale_factor_at_projection_origin, the default scale (+k_0) for planetary polar data should be set to 1.0. |
| | Polyconic | Projection is mathematically based on an infinite number of cones tangent to an infinite number of parallels. Distortion increases away from the central meridian. Has both areal and angular deformation. |
| | Robinson | Classified as a pseudocylindrical projection. Generally this projection is used for global maps. The projection is a compromise and is neither equal-area nor conformal. The meridians are gently curved leaving the poles fairly distorted. |
| | Sinusoidal | Projection is mathematically based on a cylinder tangent on the equator. Meridian spacing is equal and decreases toward the poles. Parallel spacing is equal. There is no angular deformation along the central meridian and the equator. Regional maps cannot be edge-joined in an east-west direction if each map has its own central meridian. |
| | Space Oblique Mercator | The Space Oblique Mercator (SOM) projection visually differs from the Oblique Mercator projection in that the central line (the ground-track of the orbiting satellite) is slightly curved, rather than straight. |
| | Stereographic | The Stereographic projection is geometrically projected onto a plane, and the point of the projection is on the surface of the sphere opposite the point of tangency. Circles on the body appear as straight lines, parts of circles, or circles on the projection. Directions from the center of the stereographic map projection are true. Generally only one hemisphere is portrayed. |
| | Transverse Mercator | Projection is mathematically based on a cylinder tangent to a meridian. Shape is true only within any small area. Areal enlargement increases away from the tangent meridian. Reasonably accurate projection within a 15 degree band along the line of tangency. Regional maps cannot be edge-joined in an east-west direction if each map has its own central meridian. |
| | van der Grinten | The projection has both areal and angular deformation. It was conceived as a compromise between the Mercator and the Mollweide projection, which shows the world in an ellipse. The van der Grinten shows the world in a circle. |