/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 1999-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* This package contains formulas from the PROJ package of USGS.
* USGS's work is fully acknowledged here. This derived work has
* been relicensed under LGPL with Frank Warmerdam's permission.
*/
package org.geotools.referencing.operation.projection;
import org.opengis.util.InternationalString;
import org.opengis.parameter.ParameterDescriptor;
import org.opengis.parameter.ParameterDescriptorGroup;
import org.opengis.parameter.ParameterNotFoundException;
import org.opengis.parameter.ParameterValueGroup;
import org.opengis.referencing.operation.MathTransform;
import org.opengis.referencing.operation.PlanarProjection;
import org.geotools.metadata.iso.citation.Citations;
import org.geotools.referencing.NamedIdentifier;
import org.geotools.resources.i18n.Vocabulary;
import org.geotools.resources.i18n.VocabularyKeys;
import org.geotools.util.Utilities;
import static java.lang.Math.*;
/**
* Stereographic Projection. The directions starting from the central point are true,
* but the areas and the lengths become increasingly deformed as one moves away from
* the center. This projection is used to represent polar areas. It can be adapted
* for other areas having a circular form.
* <p>
* This implementation, and its subclasses, provides transforms for six cases of the
* stereographic projection:
* <ul>
* <li>{@code "Oblique_Stereographic"} (EPSG code 9809), alias {@code "Double_Stereographic"}
* in ESRI software</li>
* <li>{@code "Stereographic"} in ESRI software (<strong>NOT</strong> EPSG code 9809)</li>
* <li>{@code "Polar_Stereographic"} (EPSG code 9810, uses a series calculation for the
* inverse)</li>
* <li>{@code "Polar_Stereographic (variant B)"} (EPSG code 9829, uses a series calculation
* for the inverse)</li>
* <li>{@code "Stereographic_North_Pole"} in ESRI software (uses iteration for the inverse)</li>
* <li>{@code "Stereographic_South_Pole"} in ESRI software (uses iteration for the inverse)</li>
* </ul>
* <p>
* Both the {@code "Oblique_Stereographic"} and {@code "Stereographic"}
* projections are "double" projections involving two parts: 1) a conformal
* transformation of the geographic coordinates to a sphere and 2) a spherical
* Stereographic projection. The EPSG considers both methods to be valid, but
* considers them to be a different coordinate operation methods.
* <p>
* The {@code "Stereographic"} case uses the USGS equations of Snyder.
* This employs a simplified conversion to the conformal sphere that
* computes the conformal latitude of each point on the sphere.
* <p>
* The {@code "Oblique_Stereographic"} case uses equations from the EPSG.
* This uses a more generalized form of the conversion to the conformal sphere; using only
* a single conformal sphere at the origin point. Since this is a "double" projection,
* it is sometimes called the "Double Stereographic". The {@code "Oblique_Stereographic"}
* is used in New Brunswick (Canada) and the Netherlands.
* <p>
* The {@code "Stereographic"} and {@code "Double_Stereographic"} names are
* used in ESRI's ArcGIS 8.x product. The {@code "Oblique_Stereographic"}
* name is the EPSG name for the later only.
* <p>
* <strong>WARNING:</strong> Tests points calculated with ArcGIS's {@code "Double_Stereographic"}
* are not always equal to points calculated with the {@code "Oblique_Stereographic"}.
* However, where there are differences, two different implementations of these equations
* (EPSG guidence note 7 and {@code libproj}) calculate the same values as we do. Until these
* differences are resolved, please be careful when using this projection.
* <p>
* If a {@link Stereographic.Provider#LATITUDE_OF_ORIGIN "latitude_of_origin"} parameter is
* supplied and is not consistent with the projection classification (for example a latitude
* different from ±90° for the polar case), then the oblique or polar case will be
* automatically inferred from the latitude. In other words, the latitude of origin has
* precedence on the projection classification. If ommited, then the default value is 90°N
* for {@code "Polar_Stereographic"} and 0° for {@code "Oblique_Stereographic"}.
* <p>
* Polar projections that use the series equations for the inverse calculation will
* be little bit faster, but may be a little bit less accurate. If a polar
* {@link Stereographic.Provider#LATITUDE_OF_ORIGIN "latitude_of_origin"} is used for
* the {@code "Oblique_Stereographic"} or {@code "Stereographic"}, the iterative
* equations will be used for inverse polar calculations.
* <p>
* The {@code "Polar Stereographic (variant B)"}, {@code "Stereographic_North_Pole"},
* and {@code "Stereographic_South_Pole"} cases include a
* {@link StereographicPole.ProviderB#STANDARD_PARALLEL "standard_parallel_1"} parameter.
* This parameter sets the latitude with a scale factor equal to the supplied
* scale factor. The {@code "Polar Stereographic (variant A)"} receives its
* {@code "latitude_of_origin"} parameter value from the hemisphere of the
* {@link StereographicPole.Provider#LATITUDE_OF_ORIGIN "latitude_of_origin"} value
* (i.e. the value is forced to ±90°).
* <p>
* <b>References:</b>
* <ul>
* <li>John P. Snyder (Map Projections - A Working Manual,<br>
* U.S. Geological Survey Professional Paper 1395, 1987)</li>
* <li>"Coordinate Conversions and Transformations including Formulas",<br>
* EPSG Guidence Note Number 7, Version 19.</li>
* <li>Gerald Evenden. <A HREF="http://members.bellatlantic.net/~vze2hc4d/proj4/sterea.pdf">
* "Supplementary PROJ.4 Notes - Oblique Stereographic Alternative"</A></li>
* <li>Krakiwsky, E.J., D.B. Thomson, and R.R. Steeves. 1977. A Manual
* For Geodetic Coordinate Transformations in the Maritimes.
* Geodesy and Geomatics Engineering, UNB. Technical Report No. 48.</li>
* <li>Thomson, D.B., M.P. Mepham and R.R. Steeves. 1977.
* The Stereographic Double Projection.
* Geodesy and Geomatics Engineereng, UNB. Technical Report No. 46.</li>
* </ul>
*
* @see <A HREF="http://mathworld.wolfram.com/StereographicProjection.html">Stereographic projection on MathWorld</A>
* @see <A HREF="http://www.remotesensing.org/geotiff/proj_list/polar_stereographic.html">Polar_Stereographic</A>
* @see <A HREF="http://www.remotesensing.org/geotiff/proj_list/oblique_stereographic.html">Oblique_Stereographic</A>
* @see <A HREF="http://www.remotesensing.org/geotiff/proj_list/stereographic.html">Stereographic</A>
* @see <A HREF="http://www.remotesensing.org/geotiff/proj_list/random_issues.html#stereographic">Some Random Stereographic Issues</A>
*
* @since 2.1
*
*
* @source $URL$
* @version $Id$
* @author André Gosselin
* @author Martin Desruisseaux (PMO, IRD)
* @author Rueben Schulz
*/
public abstract class Stereographic extends MapProjection {
/**
* For compatibility with different versions during deserialization.
*/
private static final long serialVersionUID = -176731870235252852L;
/**
* Maximum difference allowed when comparing real numbers.
*/
private static final double EPSILON = 1E-6;
/**
* The parameter descriptor group to be returned by {@link #getParameterDescriptors()}.
*/
private final ParameterDescriptorGroup descriptor;
/**
* Creates a transform from the specified group of parameter values.
*
* @param parameters The group of parameter values.
* @param descriptor The expected parameter descriptor.
* @throws ParameterNotFoundException if a required parameter was not found.
*/
Stereographic(final ParameterValueGroup parameters, final ParameterDescriptorGroup descriptor)
throws ParameterNotFoundException
{
// Fetch parameters
super(parameters, descriptor.descriptors());
this.descriptor = descriptor;
}
/**
* {@inheritDoc}
*/
public ParameterDescriptorGroup getParameterDescriptors() {
return descriptor;
}
/**
* Compares the specified object with this map projection for equality.
*/
@Override
public boolean equals(final Object object) {
/*
* Implementation note: usually, we define this method in the last subclass, which may
* compare every fields. However, all fields in subclasses like StereographicUSGS are
* fully determined by the parameters like "latitude_of_origin", which are already
* compared by super.equals(object). Comparing those derived fields would be redundant.
*/
if (object == this) {
// Slight optimization
return true;
}
if (super.equals(object)) {
final Stereographic that = (Stereographic) object;
return Utilities.equals(this.descriptor, that.descriptor);
}
return false;
}
//////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////
//////// ////////
//////// PROVIDERS ////////
//////// ////////
//////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////////////////////////
/**
* The {@linkplain org.geotools.referencing.operation.MathTransformProvider math transform
* provider} for a {@linkplain Stereographic Stereographic} projections using USGS equations.
* This is <strong>not</strong> the provider for EPSG 9809. For the later, use
* {@link ObliqueStereographic.Provider} instead.
*
* @since 2.4
* @version $Id$
* @author Rueben Schulz
*
* @see org.geotools.referencing.operation.DefaultMathTransformFactory
*/
public static class Provider extends AbstractProvider {
/**
* For compatibility with different versions during deserialization.
*/
private static final long serialVersionUID = 1243300263948365065L;
/**
* The localized name for stereographic projection.
*/
static final InternationalString NAME =
Vocabulary.formatInternational(VocabularyKeys.STEREOGRAPHIC_PROJECTION);
/**
* The parameters group.
*/
static final ParameterDescriptorGroup PARAMETERS = createDescriptorGroup(new NamedIdentifier[] {
new NamedIdentifier(Citations.ESRI, "Stereographic"),
new NamedIdentifier(Citations.GEOTIFF, "CT_Stereographic"),
new NamedIdentifier(Citations.GEOTOOLS, NAME)
}, new ParameterDescriptor[] {
SEMI_MAJOR, SEMI_MINOR,
CENTRAL_MERIDIAN, LATITUDE_OF_ORIGIN,
SCALE_FACTOR,
FALSE_EASTING, FALSE_NORTHING
});
/**
* Constructs a new provider with default parameters for EPSG stereographic oblique.
*/
public Provider() {
this(PARAMETERS);
}
/**
* Constructs a math transform provider from a set of parameters. The provider
* {@linkplain #getIdentifiers identifiers} will be the same than the parameter
* ones.
*
* @param parameters The set of parameters (never {@code null}).
*/
protected Provider(final ParameterDescriptorGroup parameters) {
super(parameters);
}
/**
* Returns the operation type for this map projection.
*/
@Override
public Class<PlanarProjection> getOperationType() {
return PlanarProjection.class;
}
/**
* Creates a transform from the specified group of parameter values.
*
* @param parameters The group of parameter values.
* @return The created math transform.
* @throws ParameterNotFoundException if a required parameter was not found.
*/
protected MathTransform createMathTransform(final ParameterValueGroup parameters)
throws ParameterNotFoundException
{
// Values here are in radians (the standard units for the map projection package)
final double latitudeOfOrigin = abs(AbstractProvider.doubleValue(LATITUDE_OF_ORIGIN, parameters));
final boolean isSpherical = isSpherical(parameters);
final ParameterDescriptorGroup descriptor = getParameters();
// Polar case.
if (abs(latitudeOfOrigin - PI/2) < EPSILON) {
if (isSpherical) {
return new PolarStereographic.Spherical(parameters, descriptor, null);
} else {
return new PolarStereographic(parameters, descriptor, null);
}
} else
// Equatorial case.
if (latitudeOfOrigin < EPSILON) {
if (isSpherical) {
return new EquatorialStereographic.Spherical(parameters, descriptor);
} else {
return createMathTransform(parameters, descriptor);
}
} else
// Generic (oblique) case.
if (isSpherical) {
return new StereographicUSGS.Spherical(parameters, descriptor);
} else {
return createMathTransform(parameters, descriptor);
}
}
/**
* Creates the general case. To be overriden by the EPSG case only.
*/
MathTransform createMathTransform(final ParameterValueGroup parameters,
final ParameterDescriptorGroup descriptor)
throws ParameterNotFoundException
{
return new StereographicUSGS(parameters, descriptor);
}
}
}