Added possibility to set custom ellipsoid

qgis · Sep 3, 2012 · 6154f8e · 6154f8e
1 parent 143300d
commit 6154f8e
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Showing 3 changed files with 27 additions and 0 deletions.
diff --git a/src/core/qgsdistancearea.cpp b/src/core/qgsdistancearea.cpp
@@ -79,6 +79,9 @@ void QgsDistanceArea::_copy( const QgsDistanceArea & origDA )
   mSemiMajor = origDA.mSemiMajor;
   mSemiMinor = origDA.mSemiMinor;
   mInvFlattening = origDA.mInvFlattening;
+  // Some calculations and trig. Should not be TOO time consuming.
+  // Alternatively we could copy the temp vars?
+  computeAreaInit();
   mSourceRefSys = origDA.mSourceRefSys;
   mCoordTransform = new QgsCoordinateTransform( origDA.mCoordTransform->sourceCrs(), origDA.mCoordTransform->destCRS() );
 }
@@ -205,6 +208,22 @@ bool QgsDistanceArea::setEllipsoid( const QString& ellipsoid )
   return true;
 }
 
+//! Sets ellipsoid by supplied radii
+// Inverse flattening is calculated with invf = a/(a-b)
+// Also, b = a-(a/invf)
+bool  QgsDistanceArea::setEllipsoid( double semiMajor, double semiMinor )
+{
+  mEllipsoid = "PARAMETER";
+  mSemiMajor = semiMajor;
+  mSemiMinor = semiMinor;
+  mInvFlattening = mSemiMajor / ( mSemiMajor - mSemiMinor );
+
+  computeAreaInit();
+
+  return true;
+}
+
+
 
 double QgsDistanceArea::measure( QgsGeometry* geometry )
 {

diff --git a/src/core/qgsdistancearea.h b/src/core/qgsdistancearea.h
@@ -71,6 +71,10 @@ class CORE_EXPORT QgsDistanceArea
     //! sets ellipsoid by its acronym
     bool setEllipsoid( const QString& ellipsoid );
 
+    //! Sets ellipsoid by supplied radii
+    // Inverse flattening is calculated with invf = a/(a-b)
+    bool setEllipsoid( double semiMajor, double semiMinor );
+
     //! returns ellipsoid's acronym
     const QString& ellipsoid() { return mEllipsoid; }
 

diff --git a/tests/src/core/testqgsdistancearea.cpp b/tests/src/core/testqgsdistancearea.cpp
@@ -81,6 +81,10 @@ void TestQgsDistanceArea::basic()
   QCOMPARE( resultB, resultC );
   delete daC;
 
+  // Use parameter setting of ellipsoid radii (from WGS72 )
+  daA.setEllipsoid( 6378135.0, 6378135.0 - ( 6378135.0 / 298.26 ) );
+  resultA = daA.measureLine( p1, p2 );
+  QCOMPARE( resultA, resultB );
 };
 
 void TestQgsDistanceArea::test_distances()