ucar.unidata.geoloc.projection.proj4.CylindricalEqualAreaProjection Maven / Gradle / Ivy

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/*
Copyright 2006 Jerry Huxtable

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
 */

/*
 * This file was semi-automatically converted from the public-domain USGS PROJ source.
 */

/**
 * Changes by Bernhard Jenny, May 2007: added missing toString() and 
 * isEqualArea(); this class now derives from CylindricalProjection instead of
 * Projection; removed isRectilinear, which is defined in the new superclass
 * CylindricalProjection; and removed trueScaleLatitude that did hide a field
 * of the Projection class of the same name.
 */

package ucar.unidata.geoloc.projection.proj4;

import ucar.nc2.constants.CDM;
import ucar.nc2.constants.CF;
import ucar.unidata.geoloc.*;

/**
 * CylindricalEqualArea Projection.
 * Port from proj4.
 */
public class CylindricalEqualAreaProjection extends ProjectionImpl {

  private double trueScaleLatitude, lon0; // degrees
  private double scaleFactor;
  private double projectionLongitude; // radians
  private double falseEasting;
  private double falseNorthing;
  private Earth earth;
  private double e;
  private double one_es;
  private double totalScale;

  private double qp;
  private double[] apa;

  public CylindricalEqualAreaProjection() {
    this(0.0, 0.0, 0.0, 0.0, new Earth());
  }

  public CylindricalEqualAreaProjection(double lon0, double trueScaleLatitude, double falseEasting, double falseNorthing, Earth earth) {
    super("CylindricalEqualAreaProjection", false);

    this.lon0 = lon0;

    this.projectionLongitude = Math.toRadians(lon0);
    this.trueScaleLatitude = trueScaleLatitude;

    this.falseEasting = falseEasting;
    this.falseNorthing = falseNorthing;

    this.earth = earth;
    this.e = earth.getEccentricity();
    double es = earth.getEccentricitySquared();
    this.one_es = 1 - es;
    this.totalScale = earth.getMajor() * .001; // scale factor for cartesion coords in km.

    double t = Math.toRadians(trueScaleLatitude);
    scaleFactor = Math.cos(t);

    if (es != 0) {
      t = Math.sin(t);
      scaleFactor /= Math.sqrt(1. - es * t * t);
      apa = MapMath.authset(es);
      qp = MapMath.qsfn(1., e, one_es);
    }

    addParameter(CF.GRID_MAPPING_NAME, CF.ALBERS_CONICAL_EQUAL_AREA);
    addParameter(CF.LONGITUDE_OF_CENTRAL_MERIDIAN, lon0);
    addParameter(CF.STANDARD_PARALLEL, trueScaleLatitude);

    if ((falseEasting != 0.0) || (falseNorthing != 0.0)) {
      addParameter(CF.FALSE_EASTING, falseEasting);
      addParameter(CF.FALSE_NORTHING, falseNorthing);
      addParameter(CDM.UNITS, "km");
    }

    addParameter(CF.SEMI_MAJOR_AXIS, earth.getMajor());
    addParameter(CF.INVERSE_FLATTENING, 1.0/earth.getFlattening());
  }

  @Override
  public ProjectionImpl constructCopy() {
    ProjectionImpl result =  new CylindricalEqualAreaProjection(lon0, trueScaleLatitude, falseEasting, falseNorthing, earth);
    result.setDefaultMapArea(defaultMapArea);
    result.setName(name);
    return result;
  }

  @Override
  public String paramsToString() {
    return null;
  }

  public ProjectionPoint latLonToProj(LatLonPoint latlon, ProjectionPointImpl xy) {
    double lam = Math.toRadians( latlon.getLongitude() - lon0);
    double phi = Math.toRadians( latlon.getLatitude());
    if (earth.isSpherical()) {
      xy.setLocation(scaleFactor * lam, Math.sin(phi) / scaleFactor);
    } else {
      xy.setLocation(scaleFactor * lam, .5 * MapMath.qsfn(Math.sin(phi), e, one_es) / scaleFactor);
    }

    xy.setLocation(totalScale * xy.getX() + falseEasting, totalScale * xy.getY() + falseNorthing);
    return xy;
  }

  public LatLonPoint projToLatLon(ProjectionPoint ppt, LatLonPointImpl lp) {
    double x = (ppt.getX() - falseEasting) / totalScale;  // assumes cartesion coords in km
    double y = (ppt.getY() - falseNorthing) / totalScale;

    if (earth.isSpherical()) {
      y *= scaleFactor;
      double t = Math.abs(y);

      if (t - MapMath.EPS10 <= 1.) {
        if (t >= 1.) {
          lp.setLatitude( Math.toDegrees(y < 0. ? -MapMath.HALFPI : MapMath.HALFPI));
        } else {
          lp.setLatitude( Math.toDegrees(Math.asin(y)));
        }
        lp.setLongitude(Math.toDegrees( x / scaleFactor));
      } else {
        throw new IllegalStateException();
      }
    } else {
      lp.setLatitude( Math.toDegrees(MapMath.authlat(Math.asin(2. * y * scaleFactor / qp), apa)));
      lp.setLongitude( lon0 + Math.toDegrees(  x / scaleFactor));
    }
    return lp;
  }

  @Override
  public boolean crossSeam(ProjectionPoint pt1, ProjectionPoint pt2) {
    return false;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;

    CylindricalEqualAreaProjection that = (CylindricalEqualAreaProjection) o;

    if (Double.compare(that.falseEasting, falseEasting) != 0) return false;
    if (Double.compare(that.falseNorthing, falseNorthing) != 0) return false;
    if (Double.compare(that.projectionLongitude, projectionLongitude) != 0) return false;
    if (Double.compare(that.scaleFactor, scaleFactor) != 0) return false;
    if (earth != null ? !earth.equals(that.earth) : that.earth != null) 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 = scaleFactor != +0.0d ? Double.doubleToLongBits(scaleFactor) : 0L;
    result = (int) (temp ^ (temp >>> 32));
    temp = projectionLongitude != +0.0d ? Double.doubleToLongBits(projectionLongitude) : 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));
    result = 31 * result + (earth != null ? earth.hashCode() : 0);
    return result;
  }
}