MAP_PROJ_INIT
The MAP_PROJ_INIT function initializes a mapping projection (establishes the coordinate conversion mechanism for mapping points on a globe's surface to points on a plane), using either IDL's own map projections or map projections from the U.S. Geological Survey's General Cartographic Transformation Package (GCTP). GCTP version 2.0 is included with IDL.
Note: The !MAP system variable is unaffected by MAP_PROJ_INIT. To use the map projection returned by MAP_PROJ_INIT for direct or object graphics, use the MAP_PROJ_FORWARD and MAP_PROJ_INVERSE functions to convert longitude/latitude values into Cartesian (x, y) coordinates before visualization.
This routine is written in the IDL language. Its source code can be found in map_proj_init.pro
in the lib
subdirectory of the IDL distribution.
Example
See MAP_PROJ_FORWARD for an example of using this function.
Syntax
Result = MAP_PROJ_INIT( Projection [, ELLIPSOID=value] [, /GCTP] [, LIMIT=vector] [, /RADIANS] [, /RELAXED] )
Keywords/Projection Parameters: [, CENTER_AZIMUTH=value] [, CENTER_LATITUDE=value] [, CENTER_LONGITUDE=value] [, FALSE_EASTING=value] [, FALSE_NORTHING=value] [, HEIGHT=value] [, HOM_AZIM_LONGITUDE=value] [, HOM_AZIM_ANGLE=value] [, HOM_LATITUDE1=value] [, HOM_LATITUDE2=value] [, HOM_LONGITUDE1=value] [, HOM_LONGITUDE2=value] [, IS_ZONES=value] [, IS_JUSTIFY=value] [, MERCATOR_SCALE=value] [, OEA_ANGLE=value] [, OEA_SHAPEM=value] [, OEA_SHAPEN=value] [, ROTATION=value] [, SEMIMAJOR_AXIS=value] [, SEMIMINOR_AXIS=value] [, SOM_INCLINATION=value] [, SOM_LONGITUDE=value] [, SOM_PERIOD=value] [, SOM_RATIO=value] [, SOM_FLAG=value] [, SOM_LANDSAT_NUMBER=value] [, SOM_LANDSAT_PATH=value] [, SPHERE_RADIUS=value] [, STANDARD_PARALLEL=value] [, STANDARD_PAR1=value] [, STANDARD_PAR2=value] [, SAT_TILT=value] [, TRUE_SCALE_LATITUDE=value] [, ZONE=value]
Return Value
The result is a !MAP structure containing the map parameters, which can be used as input to the map transformation functions MAP_PROJ_FORWARD and MAP_PROJ_INVERSE.
Arguments
Projection
Set this argument to either a projection index or a scalar string containing the name of the map projection, as described in following tables.
IDL projections:
# |
Projection Name |
Available Ellipsoids |
Allowed Keyword Parameters |
1 |
Stereographic |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
2 |
Orthographic |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
3 |
Lambert Conic |
Sphere |
SPHERE_RADIUS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE |
4 |
Lambert Azimuthal |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
5 |
Gnomonic |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
6 |
Azimuthal Equidistant |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
7 |
Satellite |
Sphere |
SPHERE_RADIUS, HEIGHT, SAT_TILT, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
8 |
Cylindrical |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
9 |
Mercator |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
10 |
Mollweide |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
11 |
Sinusoidal |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
12 |
Aitoff |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
13 |
Hammer Aitoff |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
14 |
Albers Equal Area Conic |
Sphere |
SPHERE_RADIUS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE |
15 |
Transverse Mercator |
All |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, MERCATOR_SCALE, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
16 |
Miller Cylindrical |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
17 |
Robinson |
Sphere |
SPHERE_RADIUS, CENTER_AZIMUTH, CENTER_LONGITUDE, CENTER_LATITUDE, ROTATION |
18 |
Lambert Ellipsoid Conic |
All |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE |
19 |
Goodes Homolosine |
Sphere |
SPHERE_RADIUS, CENTER_LONGITUDE |
GCTP projections:
# |
Name |
Allowed Map Parameters |
Notes |
---|---|---|---|
100 |
Geographic |
CENTER_LONGITUDE |
No projection. |
101 |
UTM |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, CENTER_LATITUDE, ZONE |
All ellipsoids; cylindrical; conformal; scale is reduced along the central longitude (MERCATOR_SCALE=0.9996). |
102 |
State Plane |
ZONE |
"Clarke 1866" or "GRS 1980" ellipsoid; uses either Transverse Mercator, Lambert Conformal Conic, or Hotine Oblique Mercator. |
103 |
Albers Equal Area |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; conic; equal-area; scale is true along the two standard parallels. |
104 |
Lambert Conformal Conic |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; conformal; scale is true along the two standard parallels. |
105 |
Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, TRUE_SCALE_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; cylindrical; conformal; scale is true along the true scale latitudes. |
106 |
Polar Stereographic |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, TRUE_SCALE_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; azimuthal; conformal; scale is true along the true scale latitude. |
107 |
Polyconic |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; neither conformal nor equal-area; scale is true along all parallels and along the central meridian. |
108 |
Equidistant Conic |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, STANDARD_PARALLEL, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; equidistant; scale is true along all meridians and along one standard parallel. |
208 |
Equidistant Conic |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, STANDARD_PAR1, STANDARD_PAR2, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; equidistant; scale is true along all meridians and along two standard parallels. |
109 |
Transverse Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, MERCATOR_SCALE, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; cylindrical; conformal; scale is true (or reduced) along the center longitude. |
110 |
Stereographic |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; azimuthal; conformal; scale is true at the center; directions from the center are true. |
111 |
Lambert Azimuthal |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; azimuthal; equal-area; scale is true at the center; directions from the center are true for spherical and polar ellipsoidal. |
112 |
Azimuthal Equidistant |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; azimuthal; equidistant; distances measured from the center are true; directions from the center are true; scale is true at the center. |
113 |
Gnomonic |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; also known as the Gnomic or Central projection; azimuthal and perspective; neither conformal nor equal-area; all great circles are straight lines; scale is true at the center; directions from the center are true. |
114 |
Orthographic |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; azimuthal; neither conformal nor equal-area; scale is true in the direction of latitude lines for the polar aspect; directions from the center are true. |
115 |
Near Side Perspective |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, HEIGHT, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids (default is Sphere); also known as the Vertical Perspective; azimuthal; neither conformal nor equal-area; scale is true at the center; directions from the center are true. |
116 |
Sinusoidal |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; pseudocylindrical; equal-area; scale is true along the central meridian and along all parallels. |
117 |
Equirectangular |
SPHERE_RADIUS, CENTER_LONGITUDE, TRUE_SCALE_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; also known as equidistant cylindrical; neither conformal nor equal-area; scale is true along all meridians and along the true scale latitudes. |
118 |
Miller Cylindrical |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; neither conformal nor equal-area; scale is true along the equator. |
119 |
Van der Grinten |
SPHERE_RADIUS, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; neither conformal nor equal-area; scale is true along the equator. |
120 |
Hotine Oblique Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, MERCATOR_SCALE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING, HOM_LONGITUDE1, HOM_LATITUDE1, HOM_LONGITUDE2, HOM_LATITUDE2 |
All ellipsoids; cylindrical; conformal; scale is true (or reduced) along the center line. Specified using two lat-lon points. |
220 |
Hotine Oblique Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, MERCATOR_SCALE, HOM_AZIM_ANGLE, HOM_AZIM_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; cylindrical; conformal; scale is true (or reduced) along the center line. Specified using azimuthal angle and longitude of the center. |
121 |
Robinson |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; pseudocylindrical; neither conformal nor equal-area; scale is true along the 38° parallels. |
122 |
Space Oblique Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, SOM_INCLINATION, SOM_LONGITUDE, FALSE_EASTING, FALSE_NORTHING, SOM_PERIOD, SOM_RATIO, SOM_FLAG |
All ellipsoids; modified cylindrical; basically conformal; scale is true along the groundtrack. Specified using inclination, longitude, period, ratio, and flag. |
222 |
Space Oblique Mercator |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, SOM_LANDSAT_NUMBER, SOM_LANDSAT_PATH, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; modified cylindrical; basically conformal; scale is true along the groundtrack. Specified using landsat number and path. |
123 |
Alaska Conformal |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; conformal; modified stereographic using complex algebra transformations to reduce scale variations. |
124 |
Interrupted Goode |
SPHERE_RADIUS |
Sphere only; pseudocylindrical; equal-area; scale is true along the central meridians and along all parallels. |
125 |
Mollweide |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; pseudocylindrical; equal-area; scale is true along latitudes 40°44' N and S. |
126 |
Interrupted Mollweide |
SPHERE_RADIUS |
Sphere only; pseudocylindrical; equal-area; scale is true along the 40°44' parallels. |
127 |
Hammer |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; also known as Hammer-Aitoff; based on Lambert Azimuthal; equal-area but not azimuthal; scale is true at the center. |
128 |
Wagner IV |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; pseudocylindrical; equal-area; scale is true along the 42°59' parallels. |
129 |
Wagner VII |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING |
Sphere only; modification of the Hammer; equal-area; scale is true at the center. |
130 |
Oblated Equal Area |
SPHERE_RADIUS, OEA_SHAPEM, OEA_SHAPEN, CENTER_LONGITUDE, CENTER_LATITUDE, FALSE_EASTING, FALSE_NORTHING, OEA_ANGLE |
Sphere only; equal-area; lines of constant distortion follow approximately oval or rectangular paths. |
131 |
Integerized Sinusoidal |
SPHERE_RADIUS, CENTER_LONGITUDE, FALSE_EASTING, FALSE_NORTHING, IS_ZONES, IS_JUSTIFY |
Sphere only; equal-area; same as sinusoidal but with discrete latitude bands. |
132 |
Cylindrical Equal Area |
SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, STANDARD_PARALLEL, FALSE_EASTING, FALSE_NORTHING |
All ellipsoids; cylindrical; equal-area; scale is true along the standard parallels (special cases: Lambert 0°, Behrmann 30°, Trystan Edwards 37.383°, Peters 44.138°, Gall orthographic 45°, Balthasart 50°. |
133 | GOES-R | SEMIMAJOR_AXIS, SEMIMINOR_AXIS, CENTER_LONGITUDE, HEIGHT, FALSE_EASTING, FALSE_NORTHING | All ellipsoids (default is GRS 1980); same properties as Near Side Perspective but (x, y) coordinates are in scan-angle radians. Default height is 35786023 meters. |
Keywords
Note: The following keywords apply to all projections.
ELLIPSOID
Set this keyword to either an integer code or a scalar string containing the ellipsoid name. The default value depends upon the projection selected, but is either the Clarke 1866 (ellipsoid 0), or a sphere of radius 6370.997 km (ellipsoid 19).
Note: For the GOES-R projection the default ellipsoid is GRS 1980.
The following ellipsoids are available for use with the ELLIPSOID keyword:
Index |
Name |
Semimajor axis (m) |
Semiminor axis (m) |
0 |
Clarke 1866 |
6378206.4 |
6356583.8 |
1 |
Clarke 1880 |
6378249.145 |
6356514.86955 |
2 |
Bessel |
6377397.155 |
6356078.96284 |
3 |
International 1967 |
6378157.5 |
6356772.2 |
4 |
International 1909 |
6378388.0 |
6356911.94613 |
5 |
WGS 72 |
6378135.0 |
6356750.519915 |
6 |
Everest |
6377276.3452 |
6356075.4133 |
7 |
WGS 66 |
6378145.0 |
6356759.769356 |
8 |
GRS 1980 |
6378137.0 |
6356752.31414 |
9 |
Airy |
6377563.396 |
6356256.91 |
10 |
Modified Everest |
6377304.063 |
6356103.039 |
11 |
Modified Airy |
6377340.189 |
6356034.448 |
12 |
Walbeck |
6378137.0 |
6356752.314245 |
13 |
Southeast Asia |
6378155.0 |
6356773.3205 |
14 |
Australian National |
6378160.0 |
6356774.719 |
15 |
Krassovsky |
6378245.0 |
6356863.0188 |
16 |
Hough |
6378270.0 |
6356794.343479 |
17 |
Mercury 1960 |
6378166.0 |
6356784.283666 |
18 |
Modified Mercury 1968 |
6378150.0 |
6356768.337303 |
19 |
Sphere |
6370997.0 |
6370997.0 |
20 |
Clarke IGN |
6378249.2 |
6356515.0 |
21 |
Helmert 1906 |
6378200.0 |
6356818.2 |
22 |
Modified Fischer 1960 |
6378155.0 |
6356773.3 |
23 |
South American 1969 |
6378160.0 |
6356774.7 |
24 |
WGS 84 |
6378137.0 |
6356752.314245 |
Note: For many projections, you can specify your own ellipsoid by using either the SEMIMAJOR_AXIS and SEMIMINOR_AXIS or the SPHERE_RADIUS keywords.
GCTP
Set this keyword to indicate that the GCTP library should be used for the projection. By default, MAP_PROJ_INIT uses the IDL projection library. This keyword is ignored if the projection exists only in one system (GCTP or IDL), or if the Projection argument is specified as an index.
LIMIT
Set this keyword to a four-element vector of the form
[Latmin, Lonmin, Latmax, Lonmax]
that specifies the boundaries of the region to be mapped. (Lonmin, Latmin) and (Lonmax, Latmax) are the longitudes and latitudes of two points diagonal from each other on the region's boundary.
Note: If the longitude range in LIMIT is less than or equal to 180 degrees, map clipping is performed in lat/lon coordinates before the transform. If the longitude range is greater than 180 degrees, map clipping is done in Cartesian coordinates after the transform. For non-cylindrical projections, clipping after the transformation to Cartesian coordinates means that some lat/lon points that fall outside the bounds specified by LIMIT may not be clipped. This occurs when the transformed lat/lon points fall inside the cartesian clipping rectangle.
Note: Lonmin should be in the range –180 to +180. Lonmax should be in the range –180 to +540, and must be greater than Lonmin. The total range for the map (Lonmax – Lonmin) must be 360 degrees or less.
RADIANS
Set this keyword to indicate that all parameters that represent angles are specified in radians rather than degrees.
RELAXED
If this keyword is set, any projection parameters which do not apply to the specified projection will be quietly ignored. By default, MAP_PROJ_INIT will issue errors for parameters that do not apply to the specified projection.
Projection Keywords
The following keywords apply only to some projections. Consult the tables above to determine which keywords apply to the projection you have selected.
Note: Unless the RADIANS keyword is set, all angles are measured in degrees, specified as a floating-point value.
CENTER_AZIMUTH
Set this keyword to the angle of the central azimuth, in degrees east of North. The default is 0 degrees. The pole is placed at an azimuth of CENTRAL_AZIMUTH degrees counterclockwise of North, as specified by the ROTATION keyword.
CENTER_LATITUDE
Set this keyword to the latitude of the point on the earth's surface to be mapped to the center of the projection plane. Latitude is measured in degrees North of the equator and must be in the range: -90 to +90. The default value is zero.
Note: For the GCTP UTM projection, the actual value of the center latitude is ignored, and only the sign (positive or negative) is used. If CENTER_LATITUDE is zero or greater then the UTM zone is positive (Northern hemisphere). If CENTER_LATITUDE is less than zero then the UTM zone is negative (Southern hemisphere). If ZONE is supplied then CENTER_LATITUDE is ignored.
Note: For the Hotine Oblique Mercator projection, the center latitude should not be set to 0, +90, or -90.
Note: For the GCTP Polar Stereographic projection, if the TRUE_SCALE_LATITUDE is greater than or equal to zero, the center latitude will automatically be set to +90 (the North pole). If the TRUE_SCALE_LATITUDE is less than zero, the center latitude will automatically be set to -90 (the South pole).
CENTER_LONGITUDE
Set this keyword to the longitude of the point on the earth's surface to be mapped to the center of the map projection. Longitude is measured in degrees east of the Greenwich meridian and must be in the range: -180 to +360. The default value is zero.
Note: For stereographic projections centered on the North or South pole, CENTER_LONGITUDE specifies the longitude directly below the pole.
Note: For the GCTP UTM projection, the center longitude is used to determine the UTM zone, along with the CENTER_LATITUDE to determine whether the zone is in the Northern or Southern hemisphere. If ZONE is supplied then CENTER_LONGITUDE is ignored.
FALSE_EASTING
Set this keyword to the false easting value (in meters) to be added to each x coordinate for the forward transform, or subtracted from each x coordinate for the inverse transform.
FALSE_NORTHING
Set this keyword to the false northing value (in meters) to be added to each y coordinate for the forward transform, or subtracted from each y coordinate for the inverse transform.
HEIGHT
Set this keyword to the height (in meters) above the earth's surface for satellite projections. The default values are:
- "Satellite" projection: one Earth radius (the semimajor axis)
- "Near Side Perspective" projection: 35800000 meters
- "GOES-R" projection: 35786023 meters
HOM_AZIM_LONGITUDE
Set this keyword to the longitude in degrees of the central meridian point where the azimuth occurs.
HOM_AZIM_ANGLE
Set this keyword to the azimuth angle, measured in degrees, east of a north-south line that intersects the center line. The center line is defined as the great circle path along which the Mercator cylinder touches the sphere.
HOM_LATITUDE1
Set this keyword to the latitude in degrees of the first point on the center line. The center line is defined as the great circle path along which the Mercator cylinder touches the sphere.
Note: HOM_LATITUDE1 cannot be equal to HOM_LATITUDE2.
HOM_LATITUDE2
Set this keyword to the latitude in degrees of the second point on the center line. The center line is defined as the great circle path along which the Mercator cylinder touches the sphere.
Note: HOM_LATITUDE1 cannot be equal to HOM_LATITUDE2.
HOM_LONGITUDE1
Set this keyword to the longitude in degrees of the first point on the center line. The center line is defined as the great circle path along which the Mercator cylinder touches the sphere.
HOM_LONGITUDE2
Set this keyword to the longitude in degrees of the second point on the center line. The center line is defined as the great circle path along which the Mercator cylinder touches the sphere.
IS_ZONES
Set this keyword to the number of longitudinal zones to include in the projection.
IS_JUSTIFY
Set this keyword to a flag indicating what to do with rows with an odd number of columns. The possible values are:
0 |
Indicates the extra column is on the right of the projection Y axis |
1 |
Indicates the extra column is on the left of the projection Y axis |
2 |
Calculate an even number of columns |
MERCATOR_SCALE
Set this keyword to the scale factor at the central meridian (Transverse Mercator projection) or the center of the projection (Hotine Oblique Mercator projection). For the Transverse Mercator projection, the default scale is 0.9996. For the UTM projection, the scale is fixed to 0.9996.
OEA_ANGLE
Set this keyword to the Oblated Equal Area oval rotation angle in degrees.
OEA_SHAPEM
Set this keyword to the Oblated Equal Area shape parameter m. The value of OEA_SHAPEM determines the horizontal flatness of the oblong region, and is usually set to a value between one and three.
OEA_SHAPEN
Set this keyword to the Oblated Equal Area oval shape parameter n. The value of OEA_SHAPEN determines the vertical flatness of the oblong region, and is usually set to a value between one and three.
Note: Setting both OEA_SHAPEM and OEA_SHAPEN equal to two is equivalent to using the Lambert Azimuthal projection.
ROTATION
Set this keyword to the angle through which the North direction should be rotated around the line between the earth's center and the point (CENTER_LONGITUDE, CENTER_LATITUDE). ROTATION is measured in degrees with the positive direction being clockwise rotation around the line. Values should be in the range ‑180 to +180. The default value is zero.
Note: If the center of the map is at the North pole, North is in the direction CENTER_LONGITUDE + 180. If the origin is at the South pole, North is in the direction CENTER_LONGITUDE.
SEMIMAJOR_AXIS
Set this keyword to the length (in meters) of the semimajor axis of the reference ellipsoid. The default is either the Clarke 1866 ellipsoid (6378206.4 m) or the Sphere radius (6370997 m), depending upon the projection.
SEMIMINOR_AXIS
Set this keyword to the length (in meters) of the semiminor axis of the reference ellipsoid. The default is either the Clarke 1866 ellipsoid (6356583.8 m) or the Sphere radius (6370997 m), depending upon the projection.
SOM_INCLINATION
Set this keyword to the orbit inclination angle in degrees of the ascending node, counter-clockwise from equator.
SOM_LONGITUDE
Set this keyword to the longitude in degrees of the ascending orbit at the equator.
SOM_PERIOD
Set this keyword to the period in minutes of the satellite revolution.
SOM_RATIO
Set this keyword to the Landsat ratio to compensate for confusion at the northern end of orbit. A typical value is 0.5201613.
SOM_FLAG
Set this keyword to the end of path flag for Landsat, where 0 is the start and 1 is the end.
SOM_LANDSAT_NUMBER
Set this keyword to the Landsat satellite number.
SOM_LANDSAT_PATH
Set this keyword to the Landsat path number (use 1 for Landsat 1, 2 and 3; use 2 for Landsat 4 and 5).
SPHERE_RADIUS
Set this keyword to the radius (in meters) of the reference sphere. The default is 6370997 m.
STANDARD_PARALLEL
Set this keyword to the latitude in degrees of the standard parallel along which the scale is true. The value must be between -90 and 90.
STANDARD_PAR1
Set this keyword to the latitude in degrees of the first standard parallel along which the scale is true. The value must be between -90 and 90.
Note: For Albers Equal Area and Lambert Conformal Conic projections, STANDARD_PAR1 and STANDARD_PAR2 should not be set to values that are equal and opposite.
STANDARD_PAR2
Set this keyword to the latitude in degrees of the second standard parallel along which the scale is true. The value must be between -90 and 90.
Note: For Albers Equal Area and Lambert Conformal Conic projections, STANDARD_PAR1 and STANDARD_PAR2 should not be set to values that are equal and opposite.
SAT_TILT
Set this keyword to the downward tilt in degrees of the camera, in degrees from the projection horizontal.
TRUE_SCALE_LATITUDE
Set this keyword to the latitude in degrees of true scale.
ZONE
Set this keyword to an integer giving the zone for the GCTP UTM projection or GCTP State Plane projection.
Note: For the UTM projection, you may also use the CENTER_LONGITUDE and CENTER_LATITUDE keywords to set the zone. Internally, the ZONE value will be computed from the longitude and latitude.
Note: For UTM, the zone number should be in the range -60 to -1 (Southern Hemisphere) or 1 to 60 (Northern Hemisphere).
The following table lists the allowed zones for the State Plane projection:
State |
Jurisdiction Zone |
NAD27 Zone Code |
NAD83 Zone Code |
Alabama |
East |
0101 |
0101 |
West |
0102 |
0102 |
|
Alaska |
01 through 10 |
5001 ... 5010 |
5001 ... 5010 |
Arizona |
East |
0201 |
0201 |
Central |
0202 |
0202 |
|
West |
0203 |
0203 |
|
Arkansas |
North |
0301 |
0301 |
South |
0302 |
0302 |
|
California |
01 through 07 |
0401 ... 0407 |
0401 ... 0406 |
Colorado |
North |
0501 |
0501 |
Central |
0502 |
0502 |
|
South |
0503 |
0503 |
|
Connecticut |
0600 |
0600 |
|
Delaware |
0700 |
0700 |
|
District of Columbia |
1900 |
1900 |
|
Florida |
East |
0901 |
0901 |
West |
0902 |
0902 |
|
North |
0903 |
0903 |
|
Georgia |
East |
1001 |
1001 |
West |
1002 |
1002 |
|
Hawaii |
01 through 05 |
5101 ... 5105 |
5101 ... 5105 |
Idaho |
East |
1101 |
1101 |
Central |
1102 |
1102 |
|
West |
1103 |
1103 |
|
Illinois |
East |
1201 |
1201 |
West |
1202 |
1202 |
|
Indiana |
East |
1301 |
1301 |
West |
1302 |
1302 |
|
Iowa |
North |
1401 |
1401 |
South |
1402 |
1402 |
|
Kansas |
North |
1501 |
1501 |
South |
1502 |
1502 |
|
Kentucky |
North |
1601 |
1601 |
South |
1602 |
1602 |
|
Louisiana |
North |
1701 |
1701 |
South |
1702 |
1702 |
|
Offshore |
1703 |
1703 |
|
Maine |
East |
1801 |
1801 |
West |
1802 |
1802 |
|
Maryland |
1900 |
1900 |
|
Massachusetts |
Mainland |
2001 |
2001 |
Island |
2002 |
2002 |
|
Michigan |
East (Transverse Mercator) |
2101 |
----- |
Central (Transverse Mercator) |
2102 |
----- |
|
West (Transverse Mercator) |
2103 |
----- |
|
North (Lambert) |
2111 |
2111 |
|
Central (Lambert) |
2112 |
2112 |
|
South (Lambert) |
2113 |
2113 |
|
Minnesota |
North |
2201 |
2201 |
Central |
2202 |
2202 |
|
South |
2203 |
2203 |
|
Mississippi |
East |
2301 |
2301 |
West |
2302 |
2302 |
|
Missouri |
East |
2401 |
2401 |
Central |
2402 |
2402 |
|
West |
2403 |
2403 |
|
Montana |
----- |
2500 |
|
|
North |
2501 |
----- |
Central |
2502 |
----- |
|
South |
2503 |
----- |
|
Nebraska |
----- |
2600 |
|
|
North |
2601 |
----- |
South |
2602 |
----- |
|
Nevada |
East |
2701 |
2701 |
Central |
2702 |
2702 |
|
West |
2703 |
2703 |
|
New Hampshire |
2800 |
2800 |
|
New Jersey |
2900 |
2900 |
|
New Mexico |
East |
3001 |
3001 |
Central |
3002 |
3002 |
|
West |
3003 |
3003 |
|
New York |
East |
3101 |
3101 |
Central |
3102 |
3102 |
|
West |
3103 |
3103 |
|
Long Island |
3104 |
3104 |
|
North Carolina |
3200 |
3200 |
|
North Dakota |
North |
3301 |
3301 |
South |
3302 |
3302 |
|
Ohio |
North |
3401 |
3401 |
South |
3402 |
3402 |
|
Oklahoma |
North |
3501 |
3501 |
South |
3502 |
3502 |
|
Oregon |
North |
3601 |
3601 |
South |
3602 |
3602 |
|
Pennsylvania |
North |
3701 |
3701 |
South |
3702 |
3702 |
|
Rhode Island |
3800 |
3800 |
|
South Carolina |
----- |
3900 |
|
|
North |
3901 |
----- |
South |
3902 |
----- |
|
South Dakota |
North |
4001 |
4001 |
South |
4002 |
4002 |
|
Tennessee |
4100 |
4100 |
|
Texas |
North |
4201 |
4201 |
North Central |
4202 |
4202 |
|
Central |
4203 |
4203 |
|
South Central |
4204 |
4204 |
|
South |
4205 |
4205 |
|
Utah |
North |
4301 |
4301 |
Central |
4302 |
4302 |
|
South |
4303 |
4303 |
|
Vermont |
4400 |
4400 |
|
Virginia |
North |
4501 |
4501 |
South |
4502 |
4502 |
|
Washington |
North |
4601 |
4601 |
South |
4602 |
4602 |
|
West Virginia |
North |
4701 |
4701 |
South |
4702 |
4702 |
|
Wisconsin |
North |
4801 |
4801 |
Central |
4802 |
4802 |
|
South |
4803 |
4803 |
|
Wyoming |
East |
4901 |
4901 |
East Central |
4902 |
4902 |
|
West Central |
4903 |
4903 |
|
West |
4904 |
4904 |
|
Puerto Rico |
5201 |
5200 |
|
Virgin Islands |
----- |
5200 |
|
|
St. John, St. Thomas |
5201 |
----- |
St. Croix |
5202 |
----- |
|
American Samoa |
5300 |
----- |
|
Guam |
5400 |
----- |
Version History
5.6 |
Introduced |
7.1 |
Deprecated the DATUM keyword, added the ELLIPSOID keyword |
8.0 |
Added Geographic and Cylindrical Equal Area projections, added ellipsoid support to Lambert Azimuthal |
8.6.1 |
Added ellipsoid support to Near Side Perspective projection; added GOES-R map projection. |