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.Bounds; 020import org.openstreetmap.josm.data.projection.Ellipsoid; 021import org.openstreetmap.josm.data.projection.ProjectionConfigurationException; 022 023// CHECKSTYLE.OFF: LineLength 024 025/** 026 * Projection for the SwissGrid CH1903 / L03, see <a href="https://en.wikipedia.org/wiki/Swiss_coordinate_system">Wikipedia article</a>.<br> 027 * 028 * Calculations were originally based on 029 * <a href="http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/switzerland.parsysrelated1.37696.downloadList.12749.DownloadFile.tmp/ch1903wgs84en.pdf"> 030 * simple formula</a>.<br> 031 * 032 * August 2010 update to 033 * <a href="http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/sys/refsys/switzerland.parsysrelated1.37696.downloadList.97912.DownloadFile.tmp/swissprojectionen.pdf"> 034 * this formula (rigorous formulas)</a>. 035 */ 036public class SwissObliqueMercator extends AbstractProj { 037 038 // CHECKSTYLE.ON: LineLength 039 040 private Ellipsoid ellps; 041 private double kR; 042 private double alpha; 043 private double b0; 044 private double k; 045 private double phi0; 046 047 private static final double EPSILON = 1e-11; 048 049 @Override 050 public void initialize(ProjParameters params) throws ProjectionConfigurationException { 051 super.initialize(params); 052 if (params.lat0 == null) 053 throw new ProjectionConfigurationException(tr("Parameter ''{0}'' required.", "lat_0")); 054 ellps = params.ellps; 055 initialize(params.lat0); 056 } 057 058 private void initialize(double lat0) { 059 phi0 = toRadians(lat0); 060 kR = sqrt(1 - ellps.e2) / (1 - (ellps.e2 * pow(sin(phi0), 2))); 061 alpha = sqrt(1 + (ellps.eb2 * pow(cos(phi0), 4))); 062 b0 = asin(sin(phi0) / alpha); 063 k = log(tan(PI / 4 + b0 / 2)) - alpha 064 * log(tan(PI / 4 + phi0 / 2)) + alpha * ellps.e / 2 065 * log((1 + ellps.e * sin(phi0)) / (1 - ellps.e * sin(phi0))); 066 } 067 068 @Override 069 public String getName() { 070 return tr("Swiss Oblique Mercator"); 071 } 072 073 @Override 074 public String getProj4Id() { 075 return "somerc"; 076 } 077 078 @Override 079 public double[] project(double phi, double lambda) { 080 double s = alpha * log(tan(PI / 4 + phi / 2)) - alpha * ellps.e / 2 081 * log((1 + ellps.e * sin(phi)) / (1 - ellps.e * sin(phi))) + k; 082 double b = 2 * (atan(exp(s)) - PI / 4); 083 double l = alpha * lambda; 084 085 double lb = atan2(sin(l), sin(b0) * tan(b) + cos(b0) * cos(l)); 086 double bb = asin(cos(b0) * sin(b) - sin(b0) * cos(b) * cos(l)); 087 088 double y = kR * lb; 089 double x = kR / 2 * log((1 + sin(bb)) / (1 - sin(bb))); 090 091 return new double[] {y, x}; 092 } 093 094 @Override 095 public double[] invproject(double y, double x) { 096 double lb = y / kR; 097 double bb = 2 * (atan(exp(x / kR)) - PI / 4); 098 099 double b = asin(cos(b0) * sin(bb) + sin(b0) * cos(bb) * cos(lb)); 100 double l = atan2(sin(lb), cos(b0) * cos(lb) - sin(b0) * tan(bb)); 101 102 double lambda = l / alpha; 103 double phi = b; 104 105 double prevPhi = -1000; 106 int iteration = 0; 107 // iteration to finds S and phi 108 while (abs(phi - prevPhi) > EPSILON) { 109 if (++iteration > 30) 110 throw new RuntimeException("Two many iterations"); 111 prevPhi = phi; 112 double s = 1 / alpha * (log(tan(PI / 4 + b / 2)) - k) + ellps.e 113 * log(tan(PI / 4 + asin(ellps.e * sin(phi)) / 2)); 114 phi = 2 * atan(exp(s)) - PI / 2; 115 } 116 return new double[] {phi, lambda}; 117 } 118 119 @Override 120 public Bounds getAlgorithmBounds() { 121 if (phi0 > 0) { 122 return new Bounds(-10, -40, 85, 40, false); 123 } else { 124 return new Bounds(-85, -40, 10, 40, false); 125 } 126 } 127}