circular survey node distribiution for transects optimized (delta alpha ...)

src/Wima/Circle.cc

@@ -107,7 +107,7 @@ QList<QPointF> Circle::approximate(double angleDiscretisation) const
 
 QList<QPointF> Circle::approximateSektor(int numberOfCorners, double alpha1, double alpha2) const
 {
-    if ( numberOfCorners < 3)
+    if ( numberOfCorners < 2)
         return QList<QPointF>();
     return approximateSektor((alpha2-alpha1)/double(numberOfCorners-1), alpha1, alpha2);
 }

src/Wima/CircularSurveyComplexItem.cc

@@ -481,15 +481,18 @@ void CircularSurveyComplexItem::_rebuildTransectsPhase1()
             for (int k = 0; k < entryPoints.size(); k++) {
                 double alpha1 = angle(entryPoints[k]);
                 double alpha2 = angle(exitPoints[(k+offset) % entryPoints.size()]);
+                double dAlpha = alpha2-alpha1;
+                int numNodes = int(ceil(dAlpha/dalpha)) + 1;
 
-                QList<QPointF> sectorPath = circle.approximateSektor(double(dalpha), alpha1, alpha2);
+                QList<QPointF> sectorPath = circle.approximateSektor(numNodes, alpha1, alpha2);
                 // use shortestPath() here if necessary, could be a problem if dr >>
                 if (sectorPath.size() > 0)
                     transectPath.append(sectorPath);
             }
         } else if (originInside) {
-            // circle fully inside polygon
-            QList<QPointF> sectorPath = circle.approximateSektor(double(dalpha), 0, 2*M_PI);
+            // circle fully inside polygon            
+            int numNodes = int(ceil(2*M_PI/dalpha)) + 1;
+            QList<QPointF> sectorPath = circle.approximateSektor(numNodes, 0, 2*M_PI);
             // use shortestPath() here if necessary, could be a problem if dr >>
             transectPath.append(sectorPath);
         }