001// License: GPL. For details, see LICENSE file. 002package org.openstreetmap.josm.data.projection.proj; 003 004import static java.lang.Math.PI; 005import static java.lang.Math.abs; 006import static java.lang.Math.asin; 007import static java.lang.Math.atan; 008import static java.lang.Math.atan2; 009import static java.lang.Math.cos; 010import static java.lang.Math.exp; 011import static java.lang.Math.log; 012import static java.lang.Math.pow; 013import static java.lang.Math.sin; 014import static java.lang.Math.sqrt; 015import static java.lang.Math.tan; 016import static java.lang.Math.toRadians; 017import static org.openstreetmap.josm.tools.I18n.tr; 018 019import org.openstreetmap.josm.data.projection.Ellipsoid; 020import org.openstreetmap.josm.data.projection.ProjectionConfigurationException; 021 022// CHECKSTYLE.OFF: LineLength 023 024/** 025 * Projection for the SwissGrid CH1903 / L03, see <a href="https://en.wikipedia.org/wiki/Swiss_coordinate_system">Wikipedia article</a>.<br> 026 * 027 * Calculations were originally based on 028 * <a href="http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/switzerland.parsysrelated1.37696.downloadList.12749.DownloadFile.tmp/ch1903wgs84en.pdf"> 029 * simple formula</a>.<br> 030 * 031 * August 2010 update to 032 * <a href="http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/switzerland.parsysrelated1.37696.downloadList.97912.DownloadFile.tmp/swissprojectionen.pdf"> 033 * this formula (rigorous formulas)</a>. 034 */ 035public class SwissObliqueMercator implements Proj { 036 037 // CHECKSTYLE.ON: LineLength 038 039 private Ellipsoid ellps; 040 private double kR; 041 private double alpha; 042 private double b0; 043 private double k; 044 045 private static final double EPSILON = 1e-11; 046 047 @Override 048 public void initialize(ProjParameters params) throws ProjectionConfigurationException { 049 if (params.lat0 == null) 050 throw new ProjectionConfigurationException(tr("Parameter ''{0}'' required.", "lat_0")); 051 ellps = params.ellps; 052 initialize(params.lat0); 053 } 054 055 private void initialize(double lat_0) { 056 double phi0 = toRadians(lat_0); 057 kR = sqrt(1 - ellps.e2) / (1 - (ellps.e2 * pow(sin(phi0), 2))); 058 alpha = sqrt(1 + (ellps.eb2 * pow(cos(phi0), 4))); 059 b0 = asin(sin(phi0) / alpha); 060 k = log(tan(PI / 4 + b0 / 2)) - alpha 061 * log(tan(PI / 4 + phi0 / 2)) + alpha * ellps.e / 2 062 * log((1 + ellps.e * sin(phi0)) / (1 - ellps.e * sin(phi0))); 063 } 064 065 @Override 066 public String getName() { 067 return tr("Swiss Oblique Mercator"); 068 } 069 070 @Override 071 public String getProj4Id() { 072 return "somerc"; 073 } 074 075 @Override 076 public double[] project(double phi, double lambda) { 077 078 double S = alpha * log(tan(PI / 4 + phi / 2)) - alpha * ellps.e / 2 079 * log((1 + ellps.e * sin(phi)) / (1 - ellps.e * sin(phi))) + k; 080 double b = 2 * (atan(exp(S)) - PI / 4); 081 double l = alpha * lambda; 082 083 double lb = atan2(sin(l), sin(b0) * tan(b) + cos(b0) * cos(l)); 084 double bb = asin(cos(b0) * sin(b) - sin(b0) * cos(b) * cos(l)); 085 086 double y = kR * lb; 087 double x = kR / 2 * log((1 + sin(bb)) / (1 - sin(bb))); 088 089 return new double[] {y, x}; 090 } 091 092 @Override 093 public double[] invproject(double y, double x) { 094 double lb = y / kR; 095 double bb = 2 * (atan(exp(x / kR)) - PI / 4); 096 097 double b = asin(cos(b0) * sin(bb) + sin(b0) * cos(bb) * cos(lb)); 098 double l = atan2(sin(lb), cos(b0) * cos(lb) - sin(b0) * tan(bb)); 099 100 double lambda = l / alpha; 101 double phi = b; 102 double s = 0; 103 104 double prevPhi = -1000; 105 int iteration = 0; 106 // iteration to finds S and phi 107 while (abs(phi - prevPhi) > EPSILON) { 108 if (++iteration > 30) 109 throw new RuntimeException("Two many iterations"); 110 prevPhi = phi; 111 s = 1 / alpha * (log(tan(PI / 4 + b / 2)) - k) + ellps.e 112 * log(tan(PI / 4 + asin(ellps.e * sin(phi)) / 2)); 113 phi = 2 * atan(exp(s)) - PI / 2; 114 } 115 return new double[] {phi, lambda}; 116 } 117}