Map-Projections/src/maps/Tobler.java
Justin Kunimune 5e01e339b9 Good documentation is its own reward
I tidied up the documentation on the BFGS stuff and updated my maps and
defaults to be informed by the new optimizations.
2018-01-31 13:22:22 -10:00

93 lines
3.3 KiB
Java

/**
* MIT License
*
* Copyright (c) 2017 Justin Kunimune
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package maps;
import java.util.Arrays;
import maps.Projection.Property;
import maps.Projection.Type;
import utils.Math2;
import utils.NumericalAnalysis;
/**
* A class of values and functions used to approximate the Tobler projection
*
* @author jkunimune
*/
public class Tobler {
public static final Projection TOBLER =
new Projection(
"Tobler Hyperelliptical", "An equal-area projection shaped like a hyperellipse.",
2*Math.PI, 0, 0b1001, Type.PSEUDOCYLINDRICAL, Property.EQUAL_AREA, 4,
new String[]{"Std. Parallel","alpha","K"},
new double[][] {{0,89,30}, {0,1,.46}, {1,5,3.7}}) { //optimal parameters are 30.6,.50,3.63, but these defaults are more recognizably Tobler
private static final int N = 20000;
private double alpha, kappa, epsilon; //epsilon is related to gamma, but defined somewhat differently
private double[] Z; //Z[i] = sin(phi) when y = i/(Z.length-1)
public void setParameters(double... params) {
this.height = 2/Math.pow(Math.cos(Math.toRadians(params[0])),2);
this.alpha = params[1];
this.kappa = params[2];
this.epsilon = NumericalAnalysis.simpsonIntegrate(
0, 1, this::hyperEllipse, 1./N);
this.Z = NumericalAnalysis.simpsonODESolve(
1, N, this::dZdY, 1./N);
}
public double[] project(double lat, double lon) {
final double z0 = Math.abs(Math.sin(lat));
final int i = Arrays.binarySearch(Z, z0);
final double y;
if (i >= 0)
y = i/(Z.length-1.);
else if (-i-1 >= Z.length)
y = Z[Z.length-1];
else
y = Math2.linInterp(z0, Z[-i-2], Z[-i-1], -i-2, -i-1)/
(Z.length-1.);
return new double[] {
lon * Math.abs(alpha + (1-alpha)*hyperEllipse(y)),
y * Math.signum(lat)*height/2 };
}
public double[] inverse(double x, double y) {
return new double[] {
Math.asin(Z[(int)Math.round(Math.abs(2*y/height)*(Z.length-1))])*Math.signum(y),
x / Math.abs(alpha + (1-alpha)*hyperEllipse(2*y/height)) };
}
public double dZdY(double y) {
return Math.abs((alpha + (1-alpha)*hyperEllipse(y))/
(alpha + (1-alpha)*epsilon));
}
public double hyperEllipse(double y) {
return Math.pow(1 - Math.pow(Math.abs(y),kappa), 1/kappa);
}
};
}