Changeset 9532 in josm for trunk/src/org/openstreetmap/josm/data/projection/proj/AbstractProj.java

Timestamp:

2016-01-18T22:48:40+01:00 (8 years ago)

Author:

bastiK

Message:

see #12186 - add Oblique Mercator projection
(imports pieces of code from the Geotools project)

File:

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

trunk/src/org/openstreetmap/josm/data/projection/proj/AbstractProj.java

@@ -25 +25 @@
 
     /**
+     * Difference allowed in iterative computations.
+     */
+    private static final double ITERATION_TOLERANCE = 1E-10;
+
+    /**
      * Relative iteration precision used in the <code>mlfn</code> method
      */
@@ -153 +158 @@
 
     /**
+     * Iteratively solve equation (7-9) from Snyder.
+     */
+    final double cphi2(final double ts) {
+        final double eccnth = 0.5 * e;
+        double phi = (Math.PI/2) - 2.0 * Math.atan(ts);
+        for (int i=0; i<MAXIMUM_ITERATIONS; i++) {
+            final double con  = e * Math.sin(phi);
+            final double dphi = (Math.PI/2) - 2.0*Math.atan(ts * Math.pow((1-con)/(1+con), eccnth)) - phi;
+            phi += dphi;
+            if (Math.abs(dphi) <= ITERATION_TOLERANCE) {
+                return phi;
+            }
+        }
+        throw new RuntimeException("no convergence");
+    }
+
+    /**
      * Computes function <code>f(s,c,e²) = c/sqrt(1 - s²&times;e²)</code> needed for the true scale
      * latitude (Snyder 14-15), where <var>s</var> and <var>c</var> are the sine and cosine of