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The NetCDF-Java Library is a Java interface to NetCDF files, as well as to many other types of scientific data formats.
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/*
 * 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
 * and understandings on the user. The user is granted the right, without
 * any fee or cost, to use, copy, modify, alter, enhance and distribute
 * this software, and any derivative works thereof, and its supporting
 * documentation for any purpose whatsoever, provided that this entire
 * notice appears in all copies of the software, derivative works and
 * supporting documentation.  Further, UCAR requests that the user credit
 * UCAR/Unidata in any publications that result from the use of this
 * software or in any product that includes this software. The names UCAR
 * and/or Unidata, however, may not be used in any advertising or publicity
 * to endorse or promote any products or commercial entity unless specific
 * written permission is obtained from UCAR/Unidata. The user also
 * understands that UCAR/Unidata is not obligated to provide the user with
 * any support, consulting, training or assistance of any kind with regard
 * to the use, operation and performance of this software nor to provide
 * the user with any updates, revisions, new versions or "bug fixes."
 *
 * THIS SOFTWARE IS PROVIDED BY UCAR/UNIDATA "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL UCAR/UNIDATA BE LIABLE FOR ANY SPECIAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
 * WITH THE ACCESS, USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package ucar.nc2.dataset.transform;

import ucar.nc2.dataset.CoordinateTransform;
import ucar.nc2.dataset.ProjectionCT;
import ucar.nc2.dataset.TransformType;
import ucar.nc2.dataset.NetcdfDataset;
import ucar.nc2.Variable;
import ucar.unidata.geoloc.Earth;

/**
 * Create a Stereographic Projection from the information in the Coordinate Transform Variable.
 *
 * @author caron
 */
public class Stereographic extends AbstractCoordTransBuilder {

  public String getTransformName() {
    return "stereographic";
  }

  public TransformType getTransformType() {
    return TransformType.Projection;
  }

  public CoordinateTransform makeCoordinateTransform(NetcdfDataset ds, Variable ctv) {
    double lon0 = readAttributeDouble( ctv, "longitude_of_projection_origin", Double.NaN);
    double scale = readAttributeDouble( ctv, "scale_factor_at_projection_origin", 1.0);
    double lat0 = readAttributeDouble( ctv, "latitude_of_projection_origin", 90.0);
    double false_easting = readAttributeDouble(ctv, "false_easting", 0.0);
    double false_northing = readAttributeDouble(ctv, "false_northing", 0.0);

    if ((false_easting != 0.0) || (false_northing != 0.0)) {
      double scalef = getFalseEastingScaleFactor(ds, ctv); // conversion from axis-unit to km
      false_easting *= scalef;
      false_northing *= scalef;
    }

    // these are as of CF in meters, need to be km (as false_easting...)
    double earth_radius = readAttributeDouble(ctv, "earth_radius", Earth.getRadius()) * .001;

    double semi_major_axis = readAttributeDouble(ctv, "semi_major_axis", Double.NaN) * .001;
    double semi_minor_axis = readAttributeDouble(ctv, "semi_minor_axis", Double.NaN) * .001;
    double inverse_flattening = readAttributeDouble(ctv, "inverse_flattening", 0.0);

    ucar.unidata.geoloc.ProjectionImpl proj;


    // check for ellipsoidal earth
    if (!Double.isNaN(semi_major_axis) && (!Double.isNaN(semi_minor_axis) || inverse_flattening != 0.0)) {
      Earth earth = new Earth(semi_major_axis, semi_minor_axis, inverse_flattening);
      proj = new ucar.unidata.geoloc.projection.proj4.StereographicAzimuthalProjection(lat0, lon0, scale, 90., false_easting, false_northing, earth);
    } else {
      proj = new ucar.unidata.geoloc.projection.Stereographic( lat0, lon0, scale, false_easting, false_northing);
    }
    return new ProjectionCT(ctv.getShortName(), "FGDC", proj);
  }
}