[4285] | 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 | @Override
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| 37 | public EastNorth latlon2eastNorth(LatLon ll) {
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| 38 | if (nadgrids != null) {
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| 39 | NTV2GridShift gs = new NTV2GridShift(ll);
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| 40 | nadgrids.gridShiftReverse(gs);
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| 41 | ll = new LatLon(ll.lat()+gs.getLatShiftDegrees(), ll.lon()+gs.getLonShiftPositiveEastDegrees());
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| 42 | } else {
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| 43 | ll = datum.fromWGS84(ll);
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| 44 | }
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| 45 | double[] en = proj.project(Math.toRadians(ll.lat()), Math.toRadians(ll.lon() - lon_0));
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| 46 | return new EastNorth(ellps.a * k_0 * en[0] + x_0, ellps.a * k_0 * en[1] + y_0);
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| 47 | }
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| 48 |
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| 49 | @Override
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| 50 | public LatLon eastNorth2latlon(EastNorth en) {
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| 51 | 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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| 52 | LatLon ll = new LatLon(Math.toDegrees(latlon_rad[0]), Math.toDegrees(latlon_rad[1]) + lon_0);
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| 53 | if (nadgrids != null) {
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| 54 | NTV2GridShift gs = new NTV2GridShift(ll);
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| 55 | nadgrids.gridShiftForward(gs);
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| 56 | ll = new LatLon(ll.lat()+gs.getLatShiftDegrees(), ll.lon()+gs.getLonShiftPositiveEastDegrees());
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| 57 | } else {
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| 58 | ll = datum.toWGS84(ll);
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| 59 | }
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| 60 | return ll;
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| 61 | }
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| 62 |
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| 63 | @Override
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| 64 | public double getDefaultZoomInPPD() {
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| 65 | // this will set the map scaler to about 1000 m
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| 66 | return 10;
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| 67 | }
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| 68 |
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| 69 | /**
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| 70 | * @return The EPSG Code of this CRS, null if it doesn't have one.
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| 71 | */
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| 72 | public abstract Integer getEpsgCode();
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| 73 |
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| 74 | /**
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| 75 | * Default implementation of toCode().
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| 76 | * Should be overridden, if there is no EPSG code for this CRS.
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| 77 | */
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| 78 | @Override
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| 79 | public String toCode() {
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| 80 | return "EPSG:" + getEpsgCode();
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| 81 | }
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| 82 |
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| 83 | }
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