/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
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* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
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package ucar.unidata.geoloc.projection;
import ucar.nc2.constants.CDM;
import ucar.nc2.constants.CF;
import ucar.unidata.geoloc.*;
import ucar.unidata.util.Parameter;
/**
* Albers Equal Area Conic Projection, one or two standard parallels,
* spherical earth.
* See John Snyder, Map Projections used by the USGS, Bulletin 1532,
* 2nd edition (1983), p 98
*
* @author Unidata Development Team
* @see Projection
* @see ProjectionImpl
*/
public class AlbersEqualArea extends ProjectionImpl {
private double lat0, lon0; // radians
private double par1, par2; // degrees
private double falseEasting, falseNorthing;
private final double earth_radius; // radius in km
/**
* constants from Snyder's equations
*/
private double n, C, rho0, lon0Degrees;
/**
* copy constructor - avoid clone !!
*/
public ProjectionImpl constructCopy() {
ProjectionImpl result = new AlbersEqualArea(getOriginLat(), getOriginLon(), getParallelOne(), getParallelTwo(),
getFalseEasting(), getFalseNorthing(), getEarthRadius());
result.setDefaultMapArea(defaultMapArea);
result.setName(name);
return result;
}
/**
* Constructor with default parameters
*/
public AlbersEqualArea() {
this(23, -96, 29.5, 45.5);
}
/**
* Construct a AlbersEqualArea Projection, two standard parellels.
* For the one standard parellel case, set them both to the same value.
*
* @param lat0 lat origin of the coord. system on the projection plane
* @param lon0 lon origin of the coord. system on the projection plane
* @param par1 standard parallel 1
* @param par2 standard parallel 2
* @throws IllegalArgumentException if lat0, par1, par2 = +/-90 deg
*/
public AlbersEqualArea(double lat0, double lon0, double par1, double par2) {
this(lat0, lon0, par1, par2, 0, 0, Earth.getRadius()*.001);
}
/**
* Construct a AlbersEqualArea Projection, two standard parellels.
* For the one standard parellel case, set them both to the same value.
*
* @param lat0 lat origin of the coord. system on the projection plane
* @param lon0 lon origin of the coord. system on the projection plane
* @param par1 standard parallel 1
* @param par2 standard parallel 2
* @param falseEasting false easting in km
* @param falseNorthing false easting in km
* @throws IllegalArgumentException if lat0, par1, par2 = +/-90 deg
*/
public AlbersEqualArea(double lat0, double lon0, double par1, double par2, double falseEasting, double falseNorthing) {
this(lat0, lon0, par1, par2, falseEasting, falseNorthing, Earth.getRadius()*.001);
}
/**
* Construct a AlbersEqualArea Projection, two standard parellels.
* For the one standard parellel case, set them both to the same value.
*
* @param lat0 lat origin of the coord. system on the projection plane
* @param lon0 lon origin of the coord. system on the projection plane
* @param par1 standard parallel 1
* @param par2 standard parallel 2
* @param falseEasting false easting in km
* @param falseNorthing false easting in km
* @param earth_radius radius of the earth in km
* @throws IllegalArgumentException if lat0, par1, par2 = +/-90 deg
*/
public AlbersEqualArea(double lat0, double lon0, double par1, double par2, double falseEasting, double falseNorthing, double earth_radius) {
super("AlbersEqualArea", false);
this.lat0 = Math.toRadians(lat0);
lon0Degrees = lon0;
this.lon0 = Math.toRadians(lon0);
this.par1 = par1;
this.par2 = par2;
this.falseEasting = falseEasting;
this.falseNorthing = falseNorthing;
this.earth_radius = earth_radius;
precalculate();
addParameter(CF.GRID_MAPPING_NAME, CF.ALBERS_CONICAL_EQUAL_AREA);
addParameter(CF.LATITUDE_OF_PROJECTION_ORIGIN, lat0);
addParameter(CF.LONGITUDE_OF_CENTRAL_MERIDIAN, lon0);
if (par2 == par1) {
addParameter(CF.STANDARD_PARALLEL, par1);
} else {
double[] data = new double[2];
data[0] = par1;
data[1] = par2;
addParameter(new Parameter(CF.STANDARD_PARALLEL, data));
}
if ((falseEasting != 0.0) || (falseNorthing != 0.0)) {
addParameter(CF.FALSE_EASTING, falseEasting);
addParameter(CF.FALSE_NORTHING, falseNorthing);
addParameter(CDM.UNITS, "km");
}
addParameter(CF.EARTH_RADIUS, earth_radius * 1000); // must be in meters
}
/**
* Precalculate some stuff
*/
private void precalculate() {
double par1r = Math.toRadians(this.par1);
double par2r = Math.toRadians(this.par2);
if (Math.abs(par2 - par1) < TOLERANCE) { // single parallel
n = Math.sin(par1r);
} else {
n = (Math.sin(par1r) + Math.sin(par2r)) / 2.0;
}
double c2 = Math.pow(Math.cos(par1r), 2);
C = c2 + 2 * n * Math.sin(par1r);
rho0 = computeRho(lat0);
}
/**
* Compute the RHO parameter
*
* @param lat latitude
* @return the rho parameter
*/
private double computeRho(double lat) {
return earth_radius * Math.sqrt(C - 2 * n * Math.sin(lat)) / n;
}
/**
* Compute theta
*
* @param lon longitude
* @return theta
*/
private double computeTheta(double lon) {
double dlon = LatLonPointImpl.lonNormal(Math.toDegrees(lon) - lon0Degrees);
return n * Math.toRadians(dlon);
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
AlbersEqualArea that = (AlbersEqualArea) o;
if (Double.compare(that.earth_radius, earth_radius) != 0) return false;
if (Double.compare(that.falseEasting, falseEasting) != 0) return false;
if (Double.compare(that.falseNorthing, falseNorthing) != 0) return false;
if (Double.compare(that.lat0, lat0) != 0) return false;
if (Double.compare(that.lon0, lon0) != 0) return false;
if (Double.compare(that.par1, par1) != 0) return false;
if (Double.compare(that.par2, par2) != 0) return false;
if ((defaultMapArea == null) != (that.defaultMapArea == null)) return false; // common case is that these are null
if (defaultMapArea != null && !that.defaultMapArea.equals(defaultMapArea)) return false;
return true;
}
@Override
public int hashCode() {
int result;
long temp;
temp = lat0 != +0.0d ? Double.doubleToLongBits(lat0) : 0L;
result = (int) (temp ^ (temp >>> 32));
temp = lon0 != +0.0d ? Double.doubleToLongBits(lon0) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
temp = par1 != +0.0d ? Double.doubleToLongBits(par1) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
temp = par2 != +0.0d ? Double.doubleToLongBits(par2) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
temp = falseEasting != +0.0d ? Double.doubleToLongBits(falseEasting) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
temp = falseNorthing != +0.0d ? Double.doubleToLongBits(falseNorthing) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
temp = earth_radius != +0.0d ? Double.doubleToLongBits(earth_radius) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
return result;
}
// bean properties
/**
* Get the second standard parallel
*
* @return the second standard parallel
*/
public double getParallelTwo() {
return par2;
}
/**
* Get the first standard parallel
*
* @return the first standard parallel
*/
public double getParallelOne() {
return par1;
}
/**
* Get the origin longitude.
*
* @return the origin longitude.
*/
public double getOriginLon() {
return Math.toDegrees(lon0);
}
/**
* Get the origin latitude.
*
* @return the origin latitude.
*/
public double getOriginLat() {
return Math.toDegrees(lat0);
}
//////////////////////////////////////////////
// setters for IDV serialization - do not use except for object creating
/**
* Set the second standard parallel
*
* @param par the second standard parallel
*/
public void setParallelTwo(double par) {
par2 = par;
precalculate();
}
/**
* Set the first standard parallel
*
* @param par the first standard parallel
*/
public void setParallelOne(double par) {
par1 = par;
precalculate();
}
/**
* Set the origin longitude.
* @param lon the origin longitude.
*/
public void setOriginLon(double lon) {
lon0 = Math.toRadians(lon);
precalculate();
}
/**
* Set the origin latitude.
*
* @param lat the origin latitude.
*/
public void setOriginLat(double lat) {
lat0 = Math.toRadians(lat);
precalculate();
}
/**
* Set the false_easting, in km.
* natural_x_coordinate + false_easting = x coordinate
*
* @param falseEasting x offset
*/
public void setFalseEasting(double falseEasting) {
this.falseEasting = falseEasting;
}
/**
* Set the false northing, in km.
* natural_y_coordinate + false_northing = y coordinate
*
* @param falseNorthing y offset
*/
public void setFalseNorthing(double falseNorthing) {
this.falseNorthing = falseNorthing;
}
//////////////////////////////////////////////
/**
* Get the false easting, in km.
*
* @return the false easting.
*/
public double getFalseEasting() {
return falseEasting;
}
/**
* Get the false northing, in km.
*
* @return the false northing.
*/
public double getFalseNorthing() {
return falseNorthing;
}
/**
* Earth radius in km
* @return Earth radius in km
*/
public double getEarthRadius() {
return this.earth_radius;
}
/**
* Get the label to be used in the gui for this type of projection
*
* @return Type label
*/
public String getProjectionTypeLabel() {
return "Albers Equal Area";
}
/**
* Create a String of the parameters.
*
* @return a String of the parameters
*/
public String paramsToString() {
return toString();
}
@Override
public String toString() {
return "AlbersEqualArea{" +
"lat0=" + lat0 +
", lon0=" + lon0 +
", par1=" + par1 +
", par2=" + par2 +
", falseEasting=" + falseEasting +
", falseNorthing=" + falseNorthing +
", earth_radius=" + earth_radius +
'}';
}
/**
* Get the scale at the given lat.
*
* @param lat lat to use
* @return scale factor at that latitude
*/
public double getScale(double lat) {
lat = Math.toRadians(lat);
double n = Math.cos(lat);
double d = Math.sqrt(C - 2 * n * Math.sin(lat));
return n / d;
}
/**
* This returns true when the line between pt1 and pt2 crosses the seam.
* When the cone is flattened, the "seam" is lon0 +- 180.
*
* @param pt1 point 1
* @param pt2 point 2
* @return true when the line between pt1 and pt2 crosses the seam.
*/
public boolean crossSeam(ProjectionPoint pt1, ProjectionPoint pt2) {
// either point is infinite
if (ProjectionPointImpl.isInfinite(pt1)
|| ProjectionPointImpl.isInfinite(pt2)) {
return true;
}
// opposite signed X values, larger then 5000 km
return (pt1.getX() * pt2.getX() < 0)
&& (Math.abs(pt1.getX() - pt2.getX()) > 5000.0);
}
/*MACROBODY
latLonToProj {} {
fromLat = Math.toRadians(fromLat);
fromLon = Math.toRadians(fromLon);
double rho = computeRho(fromLat);
double theta = computeTheta(fromLon);
toX = rho * Math.sin(theta);
toY = rho0 - rho*Math.cos(theta);
}
projToLatLon {double rrho0 = rho0;} {
if (n < 0) {
rrho0 *= -1.0;
fromX *= -1.0;
fromY *= -1.0;
}
double yd = rrho0-fromY;
double rho = Math.sqrt(fromX * fromX + yd*yd);
double theta = Math.atan2( fromX, yd);
if (n < 0) rho *= -1.0;
toLat = Math.toDegrees(Math.asin((C-Math.pow((rho*n/EARTH_RADIUS),2))/(2*n)));
toLon = Math.toDegrees(theta/n + lon0);
}
MACROBODY*/
/*BEGINGENERATED*/
/*
Note this section has been generated using the convert.tcl script.
This script, run as:
tcl convert.tcl AlbersEqualArea.java
takes the actual projection conversion code defined in the MACROBODY
section above and generates the following 6 methods
*/
/**
* Convert a LatLonPoint to projection coordinates
*
* @param latLon convert from these lat, lon coordinates
* @param result the object to write to
* @return the given result
*/
public ProjectionPoint latLonToProj(LatLonPoint latLon, ProjectionPointImpl result) {
double toX, toY;
double fromLat = latLon.getLatitude();
double fromLon = latLon.getLongitude();
fromLat = Math.toRadians(fromLat);
fromLon = Math.toRadians(fromLon);
double rho = computeRho(fromLat);
double theta = computeTheta(fromLon);
toX = rho * Math.sin(theta) + falseEasting;
toY = rho0 - rho * Math.cos(theta) + falseNorthing;
result.setLocation(toX, toY);
return result;
}
/**
* Convert projection coordinates to a LatLonPoint
* Note: a new object is not created on each call for the return value.
*
* @param world convert from these projection coordinates
* @param result the object to write to
* @return LatLonPoint convert to these lat/lon coordinates
*/
public LatLonPoint projToLatLon(ProjectionPoint world, LatLonPointImpl result) {
double toLat, toLon;
double fromX = world.getX() - falseEasting;
double fromY = world.getY() - falseNorthing;
double rrho0 = rho0;
if (n < 0) {
rrho0 *= -1.0;
fromX *= -1.0;
fromY *= -1.0;
}
double yd = rrho0 - fromY;
double rho = Math.sqrt(fromX * fromX + yd * yd);
double theta = Math.atan2(fromX, yd);
if (n < 0) {
rho *= -1.0;
}
toLat = Math.toDegrees(Math.asin((C - Math.pow((rho * n / earth_radius), 2)) / (2 * n)));
toLon = Math.toDegrees(theta / n + lon0);
result.setLatitude(toLat);
result.setLongitude(toLon);
return result;
}
/**
* Convert lat/lon coordinates to projection coordinates.
*
* @param from array of lat/lon coordinates: from[2][n],
* where from[0][i], from[1][i] is the (lat,lon)
* coordinate of the ith point
* @param to resulting array of projection coordinates,
* where to[0][i], to[1][i] is the (x,y) coordinate
* of the ith point
* @param latIndex index of latitude in "from"
* @param lonIndex index of longitude in "from"
* @return the "to" array.
*/
public float[][] latLonToProj(float[][] from, float[][] to, int latIndex,
int lonIndex) {
int cnt = from[0].length;
float[] fromLatA = from[latIndex];
float[] fromLonA = from[lonIndex];
float[] resultXA = to[INDEX_X];
float[] resultYA = to[INDEX_Y];
double toX, toY;
for (int i = 0; i < cnt; i++) {
double fromLat = fromLatA[i];
double fromLon = fromLonA[i];
fromLat = Math.toRadians(fromLat);
fromLon = Math.toRadians(fromLon);
double rho = computeRho(fromLat);
double theta = computeTheta(fromLon);
toX = rho * Math.sin(theta);
toY = rho0 - rho * Math.cos(theta);
resultXA[i] = (float) (toX + falseEasting);
resultYA[i] = (float) (toY + falseNorthing);
}
return to;
}
/**
* Convert lat/lon coordinates to projection coordinates.
*
* @param from array of lat/lon coordinates: from[2][n], where
* (from[0][i], from[1][i]) is the (lat,lon) coordinate
* of the ith point
* @param to resulting array of projection coordinates: to[2][n]
* where (to[0][i], to[1][i]) is the (x,y) coordinate
* of the ith point
* @return the "to" array
*/
public float[][] projToLatLon(float[][] from, float[][] to) {
int cnt = from[0].length;
float[] fromXA = from[INDEX_X];
float[] fromYA = from[INDEX_Y];
float[] toLatA = to[INDEX_LAT];
float[] toLonA = to[INDEX_LON];
double rrho0 = rho0;
double toLat, toLon;
for (int i = 0; i < cnt; i++) {
double fromX = fromXA[i] - falseEasting;
double fromY = fromYA[i] - falseNorthing;
if (n < 0) {
rrho0 *= -1.0;
fromX *= -1.0;
fromY *= -1.0;
}
double yd = rrho0 - fromY;
double rho = Math.sqrt(fromX * fromX + yd * yd);
double theta = Math.atan2(fromX, yd);
if (n < 0) {
rho *= -1.0;
}
toLat = Math.toDegrees(Math.asin((C
- Math.pow((rho * n / earth_radius), 2)) / (2 * n)));
toLon = Math.toDegrees(theta / n + lon0);
toLatA[i] = (float) toLat;
toLonA[i] = (float) toLon;
}
return to;
}
/**
* Convert lat/lon coordinates to projection coordinates.
*
* @param from array of lat/lon coordinates: from[2][n],
* where from[0][i], from[1][i] is the (lat,lon)
* coordinate of the ith point
* @param to resulting array of projection coordinates,
* where to[0][i], to[1][i] is the (x,y) coordinate
* of the ith point
* @param latIndex index of latitude in "from"
* @param lonIndex index of longitude in "from"
* @return the "to" array.
*/
public double[][] latLonToProj(double[][] from, double[][] to,
int latIndex, int lonIndex) {
int cnt = from[0].length;
double[] fromLatA = from[latIndex];
double[] fromLonA = from[lonIndex];
double[] resultXA = to[INDEX_X];
double[] resultYA = to[INDEX_Y];
double toX, toY;
for (int i = 0; i < cnt; i++) {
double fromLat = fromLatA[i];
double fromLon = fromLonA[i];
fromLat = Math.toRadians(fromLat);
fromLon = Math.toRadians(fromLon);
double rho = computeRho(fromLat);
double theta = computeTheta(fromLon);
toX = rho * Math.sin(theta);
toY = rho0 - rho * Math.cos(theta);
resultXA[i] = toX + falseEasting;
resultYA[i] = toY + falseNorthing;
}
return to;
}
/**
* Convert lat/lon coordinates to projection coordinates.
*
* @param from array of lat/lon coordinates: from[2][n], where
* (from[0][i], from[1][i]) is the (lat,lon) coordinate
* of the ith point
* @param to resulting array of projection coordinates: to[2][n]
* where (to[0][i], to[1][i]) is the (x,y) coordinate
* of the ith point
* @return the "to" array
*/
public double[][] projToLatLon(double[][] from, double[][] to) {
int cnt = from[0].length;
double[] fromXA = from[INDEX_X];
double[] fromYA = from[INDEX_Y];
double[] toLatA = to[INDEX_LAT];
double[] toLonA = to[INDEX_LON];
double rrho0 = rho0;
double toLat, toLon;
for (int i = 0; i < cnt; i++) {
double fromX = fromXA[i] - falseEasting;
double fromY = fromYA[i] - falseNorthing;
if (n < 0) {
rrho0 *= -1.0;
fromX *= -1.0;
fromY *= -1.0;
}
double yd = rrho0 - fromY;
double rho = Math.sqrt(fromX * fromX + yd * yd);
double theta = Math.atan2(fromX, yd);
if (n < 0) {
rho *= -1.0;
}
toLat = Math.toDegrees(Math.asin((C
- Math.pow((rho * n / earth_radius), 2)) / (2 * n)));
toLon = Math.toDegrees(theta / n + lon0);
toLatA[i] = toLat;
toLonA[i] = toLon;
}
return to;
}
/*ENDGENERATED*/
/**
* Test
*
* @param args not used
*/
public static void main(String[] args) {
AlbersEqualArea a = new AlbersEqualArea(23, -96, 29.5, 45.5);
System.out.printf("name=%s%n", a.getName());
System.out.println("ll = 35N 75W");
ProjectionPoint p = a.latLonToProj(35, -75);
System.out.println("proj point = " + p);
LatLonPoint ll = a.projToLatLon(p);
System.out.println("ll = " + ll);
}
}