[MeshGeoToolsLib] Heuristic search length.

Computes the search length using a heuristic.

MeshGeoToolsLib/HeuristicSearchLength.cpp

+/**
+ * @file
+ * @date 2014-09-19
+ * @brief Implementation of heuristic search length strategy.
+ *
+ * @copyright
+ * Copyright (c) 2012-2014, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/LICENSE.txt
+ */
+
+#include "HeuristicSearchLength.h"
+
+// ThirdParty/logog
+#include "logog/include/logog.hpp"
+
+#include "MeshLib/Elements/Element.h"
+#include "MeshLib/Elements/Line.h"
+
+namespace MeshGeoToolsLib
+{
+
+HeuristicSearchLength::HeuristicSearchLength(MeshLib::Mesh const& mesh)
+: SearchLength(mesh)
+{
+	double sum (0.0);
+	double sum_of_sqr (0.0);
+	std::size_t edge_cnt(0);
+	std::vector<MeshLib::Element*> const& elements(_mesh.getElements());
+
+	for (std::vector<MeshLib::Element*>::const_iterator it(elements.cbegin());
+			it != elements.cend(); ++it) {
+		std::size_t const n_edges((*it)->getNEdges());
+		for (std::size_t k(0); k<n_edges; k++) {
+			MeshLib::Line const* edge(static_cast<MeshLib::Line const*>((*it)->getEdge(k)));
+			if (!edge) {
+				delete edge;
+				continue;
+			}
+			double const len(edge->getLength());
+			sum += len;
+			sum_of_sqr += len*len;
+			delete edge;
+		}
+		edge_cnt += n_edges;
+	}
+
+	const double mu (sum/edge_cnt);
+	const double s (sqrt(1.0/(edge_cnt-1) * (sum_of_sqr - (sum*sum)/edge_cnt) ));
+	// heuristic to prevent negative search lengths
+	// in the case of a big standard deviation s
+	double c(2.0);
+	while (mu < c * s) {
+		c *= 0.9;
+	}
+
+	_search_length = (mu - c * s)/2;
+
+	DBUG("[MeshNodeSearcher::MeshNodeSearcher] Calculated search length for mesh \"%s\" is %f.",
+			_mesh.getName().c_str(), _search_length);
+}
+
+double HeuristicSearchLength::getSearchLength() const
+{
+	return _search_length;
+}
+
+} // end namespace MeshGeoToolsLib

MeshGeoToolsLib/HeuristicSearchLength.h

+/**
+ * @file
+ * @date 2014-09-19
+ * @brief Interface for heuristic search length strategy.
+ *
+ * @copyright
+ * Copyright (c) 2012-2014, OpenGeoSys Community (http://www.opengeosys.org)
+ *            Distributed under a Modified BSD License.
+ *              See accompanying file LICENSE.txt or
+ *              http://www.opengeosys.org/LICENSE.txt
+ */
+
+#ifndef HEURISTICSEARCHLENGTH_H_
+#define HEURISTICSEARCHLENGTH_H_
+
+#include "MeshGeoToolsLib/SearchLength.h"
+
+namespace MeshGeoToolsLib
+{
+
+/// HeuristicSearchLength implements a mesh dependent criterion for searching
+/// mesh nodes near a geometry. For this purpose it computes the average
+/// \f$\mu\f$ and the standard deviation \f$\sigma\f$ of edge length of mesh
+/// elements. The search lenght is set to \f$\mu-2\sigma\f$. This strategy
+/// is usefull for meshes with different sizes of elements.
+class HeuristicSearchLength : public SearchLength
+{
+public:
+	HeuristicSearchLength(MeshLib::Mesh const& mesh);
+	virtual double getSearchLength() const;
+};
+
+} // end namespace MeshGeoToolsLib
+
+#endif
+