/**
* 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);
double lonDiff = Math.toRadians(LatLonPointImpl.lonNormal(fromLon - lon0Degrees));
double cosc = sinLat0 * Math.sin(fromLat) + cosLat0 * Math.cos(fromLat) * Math.cos(lonDiff);
if (cosc >= 0) {
toX = R * Math.cos(fromLat) * Math.sin(lonDiff);
toY = R * (cosLat0 * Math.sin(fromLat) - sinLat0 * Math.cos(fromLat) * Math.cos(lonDiff));
} else {
toX = Double.POSITIVE_INFINITY;
toY = Double.POSITIVE_INFINITY;
}
resultXA[i] = toX;
resultYA[i] = toY;
}
return to;
}
/**
* 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 fromX = world.getX() - falseEasting;
double fromY = world.getY() - falseNorthing;
double toLon = Math.toDegrees(fromX / A) + lon0;
double e = Math.exp(-fromY / A);
double toLat = Math.toDegrees(Math.PI / 2 - 2 * Math.atan(e)); // Snyder p 44
result.setLatitude(toLat);
result.setLongitude(toLon);
return result;
}
/**
* Construct a Orthographic Projection, specify earth radius
*
* @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 earthRadius radius of the earth
* @throws IllegalArgumentException if lat0, par1, par2 = +/-90 deg
*/
public Orthographic(double lat0, double lon0, double earthRadius) {
super("Orthographic", false);
this.lat0 = Math.toRadians(lat0);
this.lon0 = Math.toRadians(lon0);
R = earthRadius;
precalculate();
addParameter(CF.GRID_MAPPING_NAME, CF.ORTHOGRAPHIC);
addParameter(CF.LATITUDE_OF_PROJECTION_ORIGIN, lat0);
addParameter(CF.LONGITUDE_OF_PROJECTION_ORIGIN, lon0);
addParameter(CF.EARTH_RADIUS, earthRadius * 1000);
}
/**
* 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);
}
/**
* 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();
double fromLat_r = Math.toRadians(fromLat);
// infinite projection
if ((Math.abs(90.0 - Math.abs(fromLat))) < TOLERANCE) {
toX = Double.POSITIVE_INFINITY;
toY = Double.POSITIVE_INFINITY;
} else {
toX = A * Math.toRadians(LatLonPointImpl.range180(fromLon - this.lon0));
toY = A * SpecialMathFunction.atanh(Math.sin(fromLat_r)); // p 41 Snyder
}
result.setLocation(toX + falseEasting, toY + falseNorthing);
return result;
}
/**
* 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);
double lonDiff = Math.toRadians(LatLonPointImpl.lonNormal(fromLon - lon0Degrees));
double cosc = sinLat0 * Math.sin(fromLat) + cosLat0 * Math.cos(fromLat) * Math.cos(lonDiff);
if (cosc >= 0) {
toX = R * Math.cos(fromLat) * Math.sin(lonDiff);
toY = R * (cosLat0 * Math.sin(fromLat) - sinLat0 * Math.cos(fromLat) * Math.cos(lonDiff));
} else {
toX = Double.POSITIVE_INFINITY;
toY = Double.POSITIVE_INFINITY;
}
result.setLocation(toX, toY);
return result;
}
/**
* Construct a Mercator Projection.
*
* @param lon0 longitude of origin (degrees)
* @param par standard parallel (degrees). cylinder cuts earth at this latitude.
* @param false_easting false_easting in km
* @param false_northing false_northing in km
* @param radius earth radius in km
*/
public Mercator(
double lon0, double par, double false_easting, double false_northing, double radius) {
super("Mercator", false);
this.lon0 = lon0;
this.par = par;
this.falseEasting = false_easting;
this.falseNorthing = false_northing;
this.earthRadius = radius;
this.par_r = Math.toRadians(par);
precalculate();
addParameter(CF.GRID_MAPPING_NAME, CF.MERCATOR);
addParameter(CF.LONGITUDE_OF_PROJECTION_ORIGIN, lon0);
addParameter(CF.STANDARD_PARALLEL, par);
addParameter(CF.EARTH_RADIUS, earthRadius * 1000);
if ((false_easting != 0.0) || (false_northing != 0.0)) {
addParameter(CF.FALSE_EASTING, false_easting);
addParameter(CF.FALSE_NORTHING, false_northing);
addParameter(CDM.UNITS, "km");
}
}
/** Precalculate some params */
private void precalculate() {
A = earthRadius * Math.cos(par_r); // incorporates the scale factor at par
}
boolean close(double d1, double d2) {
return Math.abs(d1 - d2) < TOLERENCE;
}
/**
* 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 toLat, toLon;
for (int i = 0; i < cnt; i++) {
double fromX = fromXA[i];
double fromY = fromYA[i];
double rho = Math.sqrt(fromX * fromX + fromY * fromY);
double c = Math.asin(rho / R);
toLon = lon0;
double temp = 0;
if (Math.abs(rho) > TOLERANCE) {
toLat = Math.asin(Math.cos(c) * sinLat0 + (fromY * Math.sin(c) * cosLat0 / rho));
if (Math.abs(lat0 - PI_OVER_4) > TOLERANCE) { // not 90 or -90
temp = rho * cosLat0 * Math.cos(c) - fromY * sinLat0 * Math.sin(c);
toLon = lon0 + Math.atan(fromX * Math.sin(c) / temp);
} else if (lat0 == PI_OVER_4) {
toLon = lon0 + Math.atan(fromX / -fromY);
temp = -fromY;
} else {
toLon = lon0 + Math.atan(fromX / fromY);
temp = fromY;
}
} else {
toLat = lat0;
}
toLat = Math.toDegrees(toLat);
toLon = Math.toDegrees(toLon);
if (temp < 0) {
toLon += 180;
}
toLon = LatLonPointImpl.lonNormal(toLon);
toLatA[i] = toLat;
toLonA[i] = toLon;
}
return to;
}
/**
* Get the origin longitude in degrees
*
* @return the origin longitude.
*/
public double getOriginLon() {
return Math.toDegrees(lon0);
}
/**
* 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();
double fromY = world.getY();
double rho = Math.sqrt(fromX * fromX + fromY * fromY);
double c = Math.asin(rho / R);
toLon = lon0;
double temp = 0;
if (Math.abs(rho) > TOLERANCE) {
toLat = Math.asin(Math.cos(c) * sinLat0 + (fromY * Math.sin(c) * cosLat0 / rho));
if (Math.abs(lat0 - PI_OVER_4) > TOLERANCE) { // not 90 or -90
temp = rho * cosLat0 * Math.cos(c) - fromY * sinLat0 * Math.sin(c);
toLon = lon0 + Math.atan(fromX * Math.sin(c) / temp);
} else if (lat0 == PI_OVER_4) {
toLon = lon0 + Math.atan(fromX / -fromY);
temp = -fromY;
} else {
toLon = lon0 + Math.atan(fromX / fromY);
temp = fromY;
}
} else {
toLat = lat0;
}
toLat = Math.toDegrees(toLat);
toLon = Math.toDegrees(toLon);
if (temp < 0) {
toLon += 180;
}
toLon = LatLonPointImpl.lonNormal(toLon);
result.setLatitude(toLat);
result.setLongitude(toLon);
return result;
}
/**
* Set the origin latitude.
*
* @param lat the origin latitude.
*/
public void setOriginLat(double lat) {
lat0 = Math.toRadians(lat);
precalculate();
}
/**
* Set the origin longitude.
*
* @param lon the origin longitude.
*/
public void setOriginLon(double lon) {
lon0 = Math.toRadians(lon);
precalculate();
}
/**
* Get the origin latitude in degrees
*
* @return the origin latitude.
*/
public double getOriginLat() {
return Math.toDegrees(lat0);
}
/**
* Convert "scale at standard parellel" to "standard parellel"
*
* @param scale scale at standard parallel
* @return standard parellel in degrees
*/
public static double convertScaleToStandardParallel(double scale) {
// k = 1 / cos (par); snyder p 44
// par = arccos(1/k);
double par = Math.acos(1.0 / scale);
return Math.toDegrees(par);
}
/** Precalculate some stuff */
private void precalculate() {
sinLat0 = Math.sin(lat0);
cosLat0 = Math.cos(lat0);
lon0Degrees = Math.toDegrees(lon0);
}
