The following keywords are
included as attributes in the output SD. The default projection is /CYLINDRICAL
or iproj=8. Either the projection name or number can be used
when specifying a projection method.
| projection
name |
| Keyword |
Projection |
| /STEREO |
Stereographic |
| /ORTHO |
Orthographic |
| /CONIC |
Lambert's
Conformal Conic |
| /LAMBERT |
Lambert's
Equal Area |
| /GNOMIC |
Gnomic |
| /AZIMUTHAL |
Azimuthal
Equidistant |
| /CYLIN |
Cylindrical
Equidistant |
| /MERCATOR |
Mercator |
| /MOLLWEIDE |
Mollweide |
| /SINUSOIDAL |
Sinusoidal |
| /AITOFF |
Aitoff |
| /ALBERS |
Alber's
Equal Area Conic |
| /HAMMER |
Hammer-Aitoff |
| /TRANSVERSE_MERCATOR |
Transverse
Mercator |
| /MILLER |
Miller
Cylindrical |
| /ROBINSON |
Robinson |
| /SATELLITE |
Satellite |
|
| iproj |
Numeric
value specifying a projection type. Can be used instead of projection
name keywords above.
| iproj
Value |
Projection
Type |
| 1 |
Stereographic |
| 2 |
Orthographic |
| 3 |
Lambert's
Conic |
| 4 |
Lambert |
| 5 |
Gnomic |
| 6 |
Azimuthal |
| 7 |
Satellite |
| 8 |
Cylindrical |
| 9 |
Mercator |
| 10 |
Mollweide |
| 11 |
Sinusoidal |
| 12 |
Aitoff |
| 13 |
Hammer-Aitoff |
| 14 |
Alber's
Conic |
| 15 |
Transverse
Mercator |
| 16 |
Miller
Cylindrical |
| 17 |
Robinson |
|
| xsize |
The
width of the output image size. (Default=400) |
| ysize |
The
height of the output image size. (Default=400) |
| position |
The
4-element vector [(X0, Y0), (X1, Y1)] that defines the position of the
mapped area within the output area defined by xsize and ysize.
The coordinates are in normalized units ranging from 0.0 to 1.0.
The default value is [0.0, 0.0, 1.0, 1.0] for specifying the map to fill
the whole output array defined by xsize and ysize. |
| limit |
The
four-element vector [Latmin, Lonmin, Latmax, Lonmax] that specifies the
boundaries of the region to be mapped. The default limits are the
boundaries of the input data file. |
| p0lat |
The
latitude of the point on the earth's surface to be mapped to the center
of the projection plane. The default used is projection-dependent.
In general, the default used will be the linear center of the latitude
limits specified in limit. For the following projections however,
0.0 is used as a default center:
-
Cylindrical
-
Mercator
-
Mollweide
-
Sinusoidal
-
Transverse
Mercator
-
Miller
Cylindrical
-
Robinson
|
| p0lon |
The
longitude of the point on the earth's surface to be mapped to the center
of the projection plane. The default used is projection-dependent.
In general, the default used will be the linear center of the longitude
limits specified. For the following projections however, 0.0 is used
as a default center:
|
| rot |
The
angle, measured in degrees, through which the North direction should be
rotated around the line L between the earth's center and the point (p0lat,
p0lon).
Default is 0.0 for all projections. |
| scale |
Scale
and limit are mutually exclusive. If neither are specified explicitly,
then the limit method is used. If scale is specified, then an isotropic
map on the scale 1:scale will be produced to fit dimensions [xsize,
ysize]. The resultant limits are implicit, are returned by the
mapping algorithm and are stored in the output file as an SD attribute. |
| isotropic |
Specify
either ISOTROPIC=1 or /ISOTROPIC to produce a map that has
the same scale in the X and Y direction. The default mapping behavior
is to produce a non-isotropic map in which the projection image is stretched
to fit the output size specified by [xsize, ysize]. |
| Projection-dependent
keywords |
| Central
Azimuth |
Scalar
value. The angle of the central azimuth in degrees east of north.
Only available for Cylindrical, Mercator, Miller, Mollweide and Sinusoidal
projections. The default is 0 degrees. The pole is placed at
an azimuth of CENTRAL_AZIMUTH degrees CCW of North, as specified by the
Rot argument. |
| Standard
Parallels |
Only
available for the 2 conic projections: Lambert and Albers.
A one or two-element array defining the standard parallels for conic projections. |
| Ellipsoid |
Only
available for Transverse Mercator or Lambert Conic projections. A
3-element array, [a, e^2, k], defining the ellipsoid. The default
is the Clarke 1866 ellipsoid, [6378206.4, 0.00676866, 0.9996].
-
a = equatorial
radius in meters
-
e^2 =
eccentricity squared. e^2 = 2 * f - f^2, where f = 1 - b/a (a: equatorial
radius, b: polar radius; in meters).
-
k = scale
on the central meridian.
|
|
