Index: trunk/src/org/openstreetmap/josm/data/projection/Projections.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/projection/Projections.java	(revision 9099)
+++ trunk/src/org/openstreetmap/josm/data/projection/Projections.java	(revision 9100)
@@ -27,4 +27,5 @@
 import org.openstreetmap.josm.data.projection.datum.WGS84Datum;
 import org.openstreetmap.josm.data.projection.proj.ClassProjFactory;
+import org.openstreetmap.josm.data.projection.proj.DoubleStereographic;
 import org.openstreetmap.josm.data.projection.proj.LambertConformalConic;
 import org.openstreetmap.josm.data.projection.proj.LonLat;
@@ -77,4 +78,5 @@
         registerBaseProjection("somerc", SwissObliqueMercator.class, "core");
         registerBaseProjection("tmerc", TransverseMercator.class, "core");
+        registerBaseProjection("sterea", DoubleStereographic.class, "core");
 
         ellipsoids.put("airy", Ellipsoid.Airy);
Index: trunk/src/org/openstreetmap/josm/data/projection/proj/DoubleStereographic.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/projection/proj/DoubleStereographic.java	(revision 9100)
+++ trunk/src/org/openstreetmap/josm/data/projection/proj/DoubleStereographic.java	(revision 9100)
@@ -0,0 +1,111 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.data.projection.proj;
+
+import static java.lang.Math.PI;
+import static java.lang.Math.abs;
+import static java.lang.Math.asin;
+import static java.lang.Math.atan;
+import static java.lang.Math.cos;
+import static java.lang.Math.exp;
+import static java.lang.Math.log;
+import static java.lang.Math.pow;
+import static java.lang.Math.sin;
+import static java.lang.Math.sqrt;
+import static java.lang.Math.tan;
+import static java.lang.Math.toRadians;
+import static org.openstreetmap.josm.tools.I18n.tr;
+
+import org.openstreetmap.josm.data.projection.Ellipsoid;
+import org.openstreetmap.josm.data.projection.ProjectionConfigurationException;
+
+/**
+ * Implementation of the stereographic double projection,
+ * also known as Oblique Stereographic and the Schreiber double stereographic projection.
+ *
+ * @author vholten
+ *
+ * Source: IOGP Publication 373-7-2 – Geomatics Guidance Note number 7, part 2,
+ * Sec. 1.3.7.1 Oblique and Equatorial Stereographic, http://www.epsg.org/GuidanceNotes
+ */
+
+public class DoubleStereographic implements Proj {
+
+    private Ellipsoid ellps;
+    private double e;
+    private double n;
+    private double c;
+    private double chi0;
+    private double R;
+
+    private static final double EPSILON = 1e-12;
+
+    @Override
+    public String getName() {
+        return tr("Double Stereographic");
+    }
+
+    @Override
+    public String getProj4Id() {
+        return "sterea";
+    }
+
+    @Override
+    public void initialize(ProjParameters params) throws ProjectionConfigurationException {
+        if (params.lat0 == null)
+            throw new ProjectionConfigurationException(tr("Parameter ''{0}'' required.", "lat_0"));
+        ellps = params.ellps;
+        e = ellps.e;
+        initialize(params.lat0);
+    }
+
+    private void initialize(double lat_0) {
+        double phi0 = toRadians(lat_0);
+        double e2 = ellps.e2;
+        R = sqrt(1-e2) / (1 - e2*pow(sin(phi0), 2));
+        n = sqrt(1 + ellps.eb2 * pow(cos(phi0),4));
+        double S1 = (1 + sin(phi0)) / (1 - sin(phi0));
+        double S2 = (1 - e * sin(phi0)) / (1 + e * sin(phi0));
+        double w1 = pow(S1 * pow(S2, e), n);
+        double sinchi00 = (w1 - 1) / (w1 + 1);
+        c = (n + sin(phi0)) * (1 - sinchi00) / ((n - sin(phi0)) * (1 + sinchi00));
+        double w2 = c * w1;
+        chi0 = asin((w2 - 1) / (w2 + 1));
+    }
+
+    @Override
+    public double[] project(double phi, double lambda) {
+        double Lambda = n * lambda;
+        double Sa = (1 + sin(phi)) / (1 - sin(phi));
+        double Sb = (1 - e * sin(phi)) / (1 + e * sin(phi));
+        double w = c * pow(Sa * pow(Sb, e), n);
+        double chi = asin((w - 1) / (w + 1));
+        double B = 1 + sin(chi) * sin(chi0) + cos(chi) * cos(chi0) * cos(Lambda);
+        double x = 2 * R * cos(chi) * sin(Lambda) / B;
+        double y = 2 * R * (sin(chi) * cos(chi0) - cos(chi) * sin(chi0) * cos(Lambda)) / B;
+        return new double[] {x, y};
+    }
+
+    @Override
+    public double[] invproject(double x, double y) {
+        double e2 = ellps.e2;
+        double g = 2 * R * tan(PI/4 - chi0/2);
+        double h = 4 * R * tan(chi0) + g;
+        double i = atan(x/(h + y));
+        double j = atan(x/(g - y)) - i;
+        double chi = chi0 + 2 * atan((y - x * tan(j/2)) / (2 * R));
+        double Lambda = j + 2*i;
+        double lambda = Lambda / n;
+        double psi = 0.5 * log((1 + sin(chi)) / (c*(1 - sin(chi)))) / n;
+        double phiprev = -1000;
+        int iteration = 0;
+        double phi = 2 * atan(exp(psi)) - PI/2;
+        while (abs(phi - phiprev) > EPSILON) {
+            if (++iteration > 10)
+                throw new RuntimeException("Too many iterations");
+            phiprev = phi;
+            double psii = log(tan(phi/2 + PI/4) * pow((1 - e * sin(phi)) / (1 + e * sin(phi)), e/2));
+            phi = phi - (psii - psi) * cos(phi) * (1 - e2 * pow(sin(phi), 2)) / (1 - e2);
+        }
+        return new double[] {phi, lambda};
+    }
+}
Index: trunk/src/org/openstreetmap/josm/gui/preferences/projection/ProjectionPreference.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/preferences/projection/ProjectionPreference.java	(revision 9099)
+++ trunk/src/org/openstreetmap/josm/gui/preferences/projection/ProjectionPreference.java	(revision 9100)
@@ -194,4 +194,11 @@
 
         /**
+         * Netherlands RD projection
+         *
+         * @author vholten
+         */
+        registerProjectionChoice(tr("Rijksdriehoekscoördinaten (Netherlands)"), "core:dutchrd", 28992); // NL
+
+        /**
          * PUWG 1992 and 2000 are the official cordinate systems in Poland.
          *