1 | // License: GPL. For details, see LICENSE file.
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2 | package org.openstreetmap.josm.data.projection;
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3 |
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4 | import org.openstreetmap.josm.data.projection.datum.Datum;
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5 | import org.openstreetmap.josm.data.projection.proj.Proj;
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6 | import org.openstreetmap.josm.data.coor.EastNorth;
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7 | import org.openstreetmap.josm.data.coor.LatLon;
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8 |
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9 | /**
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10 | * Implementation of the Projection interface that represents a coordinate reference system and delegates
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11 | * the real projection and datum conversion to other classes.
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12 | *
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13 | * It handles false easting and northing, central meridian and general scale factor before calling the
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14 | * delegate projection.
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15 | *
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16 | * Forwards lat/lon values to the real projection in units of radians.
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17 | *
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18 | * The fields are named after Proj.4 parameters.
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19 | *
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20 | * Subclasses of AbstractProjection must set ellps and proj to a non-null value.
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21 | * In addition, either datum or nadgrid has to be initialized to some value.
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22 | *
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23 | * FIXME: nadgrids should probably be implemented as a Datum
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24 | */
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25 | abstract public class AbstractProjection implements Projection {
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26 |
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27 | protected Ellipsoid ellps;
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28 | protected Datum datum;
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29 | protected Proj proj;
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30 | protected double x_0 = 0.0; /* false easting (in meters) */
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31 | protected double y_0 = 0.0; /* false northing (in meters) */
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32 | protected double lon_0 = 0.0; /* central meridian */
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33 | protected double k_0 = 1.0; /* general scale factor */
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34 | protected NTV2GridShiftFile nadgrids = null;
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35 |
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36 | public final Ellipsoid getEllipsoid() {
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37 | return ellps;
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38 | }
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39 |
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40 | public final Datum getDatum() {
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41 | return datum;
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42 | }
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43 |
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44 | public final Proj getProj() {
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45 | return proj;
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46 | }
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47 |
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48 | public final double getFalseEasting() {
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49 | return x_0;
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50 | }
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51 |
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52 | public final double getFalseNorthing() {
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53 | return y_0;
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54 | }
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55 |
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56 | public final double getCentralMeridian() {
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57 | return lon_0;
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58 | }
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59 |
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60 | public final double getScaleFactor() {
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61 | return k_0;
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62 | }
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63 |
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64 | @Override
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65 | public EastNorth latlon2eastNorth(LatLon ll) {
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66 | if (nadgrids != null) {
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67 | NTV2GridShift gs = new NTV2GridShift(ll);
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68 | nadgrids.gridShiftReverse(gs);
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69 | ll = new LatLon(ll.lat()+gs.getLatShiftDegrees(), ll.lon()+gs.getLonShiftPositiveEastDegrees());
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70 | } else {
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71 | ll = datum.fromWGS84(ll);
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72 | }
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73 | double[] en = proj.project(Math.toRadians(ll.lat()), Math.toRadians(ll.lon() - lon_0));
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74 | return new EastNorth(ellps.a * k_0 * en[0] + x_0, ellps.a * k_0 * en[1] + y_0);
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75 | }
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76 |
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77 | @Override
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78 | public LatLon eastNorth2latlon(EastNorth en) {
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79 | double[] latlon_rad = proj.invproject((en.east() - x_0) / ellps.a / k_0, (en.north() - y_0) / ellps.a / k_0);
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80 | LatLon ll = new LatLon(Math.toDegrees(latlon_rad[0]), Math.toDegrees(latlon_rad[1]) + lon_0);
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81 | if (nadgrids != null) {
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82 | NTV2GridShift gs = new NTV2GridShift(ll);
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83 | nadgrids.gridShiftForward(gs);
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84 | ll = new LatLon(ll.lat()+gs.getLatShiftDegrees(), ll.lon()+gs.getLonShiftPositiveEastDegrees());
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85 | } else {
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86 | ll = datum.toWGS84(ll);
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87 | }
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88 | return ll;
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89 | }
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90 |
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91 | @Override
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92 | public double getDefaultZoomInPPD() {
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93 | // this will set the map scaler to about 1000 m
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94 | return 10;
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95 | }
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96 |
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97 | /**
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98 | * @return The EPSG Code of this CRS, null if it doesn't have one.
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99 | */
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100 | public abstract Integer getEpsgCode();
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101 |
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102 | /**
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103 | * Default implementation of toCode().
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104 | * Should be overridden, if there is no EPSG code for this CRS.
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105 | */
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106 | @Override
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107 | public String toCode() {
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108 | return "EPSG:" + getEpsgCode();
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109 | }
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110 |
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111 | protected static final double convertMinuteSecond(double minute, double second) {
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112 | return (minute/60.0) + (second/3600.0);
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113 | }
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114 |
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115 | protected static final double convertDegreeMinuteSecond(double degree, double minute, double second) {
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116 | return degree + convertMinuteSecond(minute, second);
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117 | }
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118 | }
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