core/org.eclipse.stem.loggers.imagewriter/src/org/eclipse/stem/loggers/imagewriter/logger/projections/AzimuthalEquidistant.java

/*******************************************************************************
 * Copyright (c) 2011 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.stem.loggers.imagewriter.logger.projections;

import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;

/**
 * Implementation of Equirectangular map projection. In terms of the existing
 * coordinate system implied in the Globe system, this projection does nothing
 * as this is the implied base coordinate system
 * 
 * @see http://mathworld.wolfram.com/EquirectangularProjection.html
 * 
 */
public class AzimuthalEquidistant implements IMapProjection {
	private Point2D origin = new Point2D.Double(0.0, 0.0);

	private static final Rectangle2D PROJECTION_BOUNDS = new Rectangle2D.Double(
			-180, -180, 360, 360);

	/**
	 * 
	 */
	public AzimuthalEquidistant() {
		super();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.ibm.almaden.omniglobe.projection.IMapProjection#project(java.awt.
	 * geom.Point2D)
	 */
	public double[] project(double lat, double lon) 
	{
		double lam0 = Math.toRadians(origin.getX());
		double phi0 = Math.toRadians(origin.getY());

		double phi = Math.toRadians(lat);
		double lam = Math.toRadians(lon);
		
		double c = Math.acos(Math.sin(phi0)*Math.sin(phi)+Math.cos(phi0)*Math.cos(phi)*Math.cos(lam-lam0));
		double k = c / Math.sin(c);
		
		double lonNew = k*Math.cos(phi)*Math.sin(lam-lam0);
		double latNew = k*(Math.cos(phi0)*Math.sin(phi)-Math.sin(phi0)*Math.cos(phi)*Math.cos(lam-lam0));
		
		return new double[] { Math.toDegrees(latNew), Math.toDegrees(lonNew) };
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.ibm.almaden.omniglobe.projection.IMapProjection#project(java.awt.
	 * geom.Point2D, java.awt.geom.Point2D, boolean)
	 */
	public double[] project(double lat, double lon, double lat0, double lon0,
			boolean distort) {
		return project(lat, lon);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.ibm.almaden.omniglobe.projection.IMapProjection#inverseProject(java
	 * .awt.geom.Point2D)
	 */
	public double[] inverseProject(double lat, double lon) {
		return new double[] { lat, lon };
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.ibm.almaden.omniglobe.projection.IMapProjection#inverseProject(java
	 * .awt.geom.Point2D, java.awt.geom.Point2D, boolean)
	 */
	public double[] inverseProject(double lat, double lon, double lat0,
			double lon0, boolean distort) {
		return inverseProject(lat, lon);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * com.ibm.almaden.omniglobe.projection.IMapProjection#setOrigin(java.awt
	 * .geom.Point2D)
	 */
	public void setOrigin(double lat, double lon) {
		origin = new Point2D.Double(lon, lat);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.ibm.almaden.omniglobe.projection.IMapProjection#getBounds()
	 */
	public Rectangle2D getBounds() {
		return PROJECTION_BOUNDS;
	}
	
}