Changeset 9790 in josm for trunk/src/org/openstreetmap/josm/data/projection/AbstractProjection.java

Timestamp:

2016-02-12T14:31:47+01:00 (10 years ago)

Author:

bastiK

Message:

use intended units for east/north coordinates (see #12186)

When east/north coordinates are not in meter, but
feet, ... convert them to correct units.
Currently they are always stored in meters or degrees.
This makes no difference to JOSM internally, but affects
services like WMS/WMTS.
Only relevant for projections with +units=... or +to_meter=...
parameter set to non-default value.

File:

• trunk/src/org/openstreetmap/josm/data/projection/AbstractProjection.java (modified) (2 diffs)

trunk/src/org/openstreetmap/josm/data/projection/AbstractProjection.java

@@ -28 +28 @@
     protected Datum datum;
     protected Proj proj;
-    protected double x0;       /* false easting (in meters) */
-    protected double y0;       /* false northing (in meters) */
-    protected double lon0;     /* central meridian */
-    protected double pm;       /* prime meridian */
-    protected double k0 = 1.0; /* general scale factor */
+    protected double x0;            /* false easting (in meters) */
+    protected double y0;            /* false northing (in meters) */
+    protected double lon0;          /* central meridian */
+    protected double pm;            /* prime meridian */
+    protected double k0 = 1.0;      /* general scale factor */
+    protected double toMeter = 1.0; /* switch from meters to east/north coordinate units */
 
     private volatile ProjectionBounds projectionBoundsBox;
@@ -68 +69 @@
     }
 
+    /**
+     * Get the factor that converts meters to intended units of east/north coordinates.
+     *
+     * For projected coordinate systems, the semi-major axis of the ellipsoid is
+     * always given in meters, which means the preliminary projection result will
+     * be in meters as well. This factor is used to convert to the intended units
+     * of east/north coordinates (e.g. feet in the US).
+     * 
+     * For geographic coordinate systems, the preliminary "projection" result will
+     * be in degrees, so there is no reason to convert anything and this factor
+     * will by 1 by default.
+     *
+     * @return factor that converts meters to intended units of east/north coordinates
+     */
+    public final double getToMeter() {
+        return toMeter;
+    }
+
     @Override
     public EastNorth latlon2eastNorth(LatLon ll) {
         ll = datum.fromWGS84(ll);
         double[] en = proj.project(Math.toRadians(ll.lat()), Math.toRadians(LatLon.normalizeLon(ll.lon() - lon0 - pm)));
-        return new EastNorth(ellps.a * k0 * en[0] + x0, ellps.a * k0 * en[1] + y0);
+        return new EastNorth((ellps.a * k0 * en[0] + x0) / toMeter, (ellps.a * k0 * en[1] + y0) / toMeter);
     }
 
     @Override
     public LatLon eastNorth2latlon(EastNorth en) {
-        double[] latlon_rad = proj.invproject((en.east() - x0) / ellps.a / k0, (en.north() - y0) / ellps.a / k0);
+        double[] latlon_rad = proj.invproject((en.east() * toMeter - x0) / ellps.a / k0, (en.north() * toMeter - y0) / ellps.a / k0);
         LatLon ll = new LatLon(Math.toDegrees(latlon_rad[0]), LatLon.normalizeLon(Math.toDegrees(latlon_rad[1]) + lon0 + pm));
         return datum.toWGS84(ll);