ucar.unidata.geoloc.projection.sat

Class Geostationary

java.lang.Object

ucar.unidata.geoloc.projection.AbstractProjection

ucar.unidata.geoloc.projection.sat.Geostationary

All Implemented Interfaces:

Projection

@Immutable
public class Geostationary
extends AbstractProjection

Describe: https://cf-pcmdi.llnl.gov/trac/ticket/72 Accepted for CF-1.7 grid_mapping_name = geostationary Map parameters: latitude_of_projection_origin longitude_of_projection_origin perspective_point_height semi_minor_axis semi_major_axis inverse_flattening sweep_angle_axis fixed_angle_axis Map coordinates: The x (abscissa) and y (ordinate) rectangular coordinates are identified by the standard_name attribute value projection_x_coordinate and projection_y_coordinate respectively. In the case of this projection, the projection coordinates in this projection are directly related to the scanning angle of the satellite instrument, and their units are radians. Notes: The algorithm for computing the mapping may be found at http://www.eumetsat.int/idcplg?IdcService=GET_FILE&dDocName=PDF_CGMS_03&RevisionSelectionMethod=LatestReleased. This document assumes the point of observation is directly over the equator, and that the sweep_angle_axis is y. Notes on using the PROJ.4 software packages for computing the mapping may be found at http://trac.osgeo.org/proj/wiki/proj%3Dgeos and http://remotesensing.org/geotiff/proj_list/geos.html . The "perspective_point_height" is the distance to the surface of the ellipsoid. Adding the earth major axis gives the distance from the centre of the earth. The "sweep_angle_axis" attribute indicates which axis the instrument sweeps. The value = "y" corresponds to the spin-stabilized Meteosat satellites, the value = "x" to the GOES-R satellite. The "fixed_angle_axis" attribute indicates which axis the instrument is fixed. The values are opposite to "sweep_angle_axis". Only one of those two attributes are mandatory. latitude_of_projection_origin will be taken as zero (at the Equator). inverse_flattening may be specified independent of the semi_minor/major axes (GRS80). If left unspecified it will be computed from semi_minor/major_axis values.

Since:

12/5/13

Field Summary

Fields inherited from class ucar.unidata.geoloc.projection.AbstractProjection

atts, EARTH_RADIUS, INDEX_LAT, INDEX_LON, INDEX_X, INDEX_Y, isLatLon, name, PI, PI_OVER_2, PI_OVER_4, TOLERANCE

Constructor Summary

Constructors

Constructor and Description
Geostationary()
Geostationary(double subLonDegrees)
Geostationary(double subLonDegrees, boolean isSweepX)
Geostationary(double subLonDegrees, double perspective_point_height, double semi_minor_axis, double semi_major_axis, double inv_flattening, boolean isSweepX)
Geostationary(double subLonDegrees, double perspective_point_height, double semi_minor_axis, double semi_major_axis, double inv_flattening, boolean isSweepX, double geoCoordinateScaleFactor)
Geostationary(double subLonDegrees, String sweepAngleAxis, double geoCoordinateScaleFactor)

Method Summary

Modifier and Type	Method and Description
Projection	constructCopy() copy constructor - avoid clone !!
boolean	crossSeam(ProjectionPoint pt1, ProjectionPoint pt2) Does the line between these two points cross the projection "seam", which is a discontinuity in the function latlon <-> projection plane
boolean	equals(Object o)
int	hashCode()
ProjectionPoint	latLonToProj(LatLonPoint latlon) Returns an x/y grid point in projection coordinate matching a lat/lon point.
ProjectionRect	latLonToProjBB(LatLonRect rect) Create a ProjectionRect from the given LatLonRect.
String	paramsToString() String representation of the projection parameters.
LatLonPoint	projToLatLon(ProjectionPoint ppt) Convert projection coordinates to a LatLonPoint.

Methods inherited from class ucar.unidata.geoloc.projection.AbstractProjection

addParameter, addParameter, addParameter, addParameter, findProjectionParameter, getClassName, getHeader, getMinOrMaxLon, getName, getProjectionAttributes, getProjectionParameters, getProjectionTypeLabel, isLatLon, projToLatLonBB, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface ucar.unidata.geoloc.Projection

latLonToProj, projToLatLon

Constructor Detail

Geostationary

public Geostationary()

Geostationary

public Geostationary(double subLonDegrees)

Geostationary

public Geostationary(double subLonDegrees,
                     boolean isSweepX)

Geostationary

public Geostationary(double subLonDegrees,
                     String sweepAngleAxis,
                     double geoCoordinateScaleFactor)

Geostationary

public Geostationary(double subLonDegrees,
                     double perspective_point_height,
                     double semi_minor_axis,
                     double semi_major_axis,
                     double inv_flattening,
                     boolean isSweepX)

Geostationary

public Geostationary(double subLonDegrees,
                     double perspective_point_height,
                     double semi_minor_axis,
                     double semi_major_axis,
                     double inv_flattening,
                     boolean isSweepX,
                     double geoCoordinateScaleFactor)

Method Detail

constructCopy

public Projection constructCopy()

copy constructor - avoid clone !!

Specified by:

constructCopy in class AbstractProjection

Returns:

a copy of this Projection.

paramsToString

public String paramsToString()

Description copied from interface: Projection

String representation of the projection parameters.

Specified by:

paramsToString in interface Projection

Specified by:

paramsToString in class AbstractProjection

latLonToProj

public ProjectionPoint latLonToProj(LatLonPoint latlon)

Returns an x/y grid point in projection coordinate matching a lat/lon point. The units of the returned result will be in radians unless the Geostationary object was created using one of the constructors that takes a geoCoordinateScaleFactor parameter. If that parameter is provided, then the units of x and y are in radians divided by the scaling factor.

Parameters:

latlon - convert from these lat, lon coordinates

Returns:

destPoint

projToLatLon

public LatLonPoint projToLatLon(ProjectionPoint ppt)

Description copied from interface: Projection

Convert projection coordinates to a LatLonPoint.

crossSeam

public boolean crossSeam(ProjectionPoint pt1,
                         ProjectionPoint pt2)

Description copied from interface: Projection

Does the line between these two points cross the projection "seam", which is a discontinuity in the function latlon <-> projection plane

Parameters:

pt1 - the line goes between these two points

pt2 - the line goes between these two points

Returns:

false if there is no seam, or the line does not cross it.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

latLonToProjBB

public ProjectionRect latLonToProjBB(LatLonRect rect)

Create a ProjectionRect from the given LatLonRect. Handles lat/lon points that do not intersect the projection panel. LOOK NEEDS OVERRIDDING

Specified by:

latLonToProjBB in interface Projection

Overrides:

latLonToProjBB in class AbstractProjection

Parameters:

rect - the LatLonRect

Returns:

ProjectionRect, or null if no part of the LatLonRect intersects the projection plane