Quantum GIS API Documentation
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00001 /*************************************************************************** 00002 qgsidwinterpolator.cpp 00003 ---------------------- 00004 begin : Marco 10, 2008 00005 copyright : (C) 2008 by Marco Hugentobler 00006 email : marco dot hugentobler at karto dot baug dot ethz dot ch 00007 ***************************************************************************/ 00008 00009 /*************************************************************************** 00010 * * 00011 * This program is free software; you can redistribute it and/or modify * 00012 * it under the terms of the GNU General Public License as published by * 00013 * the Free Software Foundation; either version 2 of the License, or * 00014 * (at your option) any later version. * 00015 * * 00016 ***************************************************************************/ 00017 00018 #include "qgsidwinterpolator.h" 00019 #include <cmath> 00020 #include <limits> 00021 00022 QgsIDWInterpolator::QgsIDWInterpolator( const QList<LayerData>& layerData ): QgsInterpolator( layerData ), mDistanceCoefficient( 2.0 ) 00023 { 00024 00025 } 00026 00027 QgsIDWInterpolator::QgsIDWInterpolator(): QgsInterpolator( QList<LayerData>() ), mDistanceCoefficient( 2.0 ) 00028 { 00029 00030 } 00031 00032 QgsIDWInterpolator::~QgsIDWInterpolator() 00033 { 00034 00035 } 00036 00037 int QgsIDWInterpolator::interpolatePoint( double x, double y, double& result ) 00038 { 00039 if ( !mDataIsCached ) 00040 { 00041 cacheBaseData(); 00042 } 00043 00044 double currentWeight; 00045 double distance; 00046 00047 double sumCounter = 0; 00048 double sumDenominator = 0; 00049 00050 QVector<vertexData>::iterator vertex_it = mCachedBaseData.begin(); 00051 00052 for ( ; vertex_it != mCachedBaseData.end(); ++vertex_it ) 00053 { 00054 distance = sqrt(( vertex_it->x - x ) * ( vertex_it->x - x ) + ( vertex_it->y - y ) * ( vertex_it->y - y ) ); 00055 if (( distance - 0 ) < std::numeric_limits<double>::min() ) 00056 { 00057 result = vertex_it->z; 00058 return 0; 00059 } 00060 currentWeight = 1 / ( pow( distance, mDistanceCoefficient ) ); 00061 sumCounter += ( currentWeight * vertex_it->z ); 00062 sumDenominator += currentWeight; 00063 } 00064 00065 if ( sumDenominator == 0.0 ) 00066 { 00067 return 1; 00068 } 00069 00070 result = sumCounter / sumDenominator; 00071 return 0; 00072 }