QGIS API Documentation 3.27.0-Master (f261cc1f8b)
qgsidwinterpolator.cpp
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1/***************************************************************************
2 qgsidwinterpolator.cpp
3 ----------------------
4 begin : Marco 10, 2008
5 copyright : (C) 2008 by Marco Hugentobler
6 email : marco dot hugentobler at karto dot baug dot ethz dot ch
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
18#include "qgsidwinterpolator.h"
19#include "qgis.h"
20#include <cmath>
21#include <limits>
22
23QgsIDWInterpolator::QgsIDWInterpolator( const QList<LayerData> &layerData )
24 : QgsInterpolator( layerData )
25{}
26
27int QgsIDWInterpolator::interpolatePoint( double x, double y, double &result, QgsFeedback *feedback )
28{
29 if ( !mDataIsCached )
30 {
31 cacheBaseData( feedback );
32 }
33
34 double sumCounter = 0;
35 double sumDenominator = 0;
36
37 for ( const QgsInterpolatorVertexData &vertex : std::as_const( mCachedBaseData ) )
38 {
39 double distance = std::sqrt( ( vertex.x - x ) * ( vertex.x - x ) + ( vertex.y - y ) * ( vertex.y - y ) );
40 if ( qgsDoubleNear( distance, 0.0 ) )
41 {
42 result = vertex.z;
43 return 0;
44 }
45 double currentWeight = 1 / ( std::pow( distance, mDistanceCoefficient ) );
46 sumCounter += ( currentWeight * vertex.z );
47 sumDenominator += currentWeight;
48 }
49
50 if ( sumDenominator == 0.0 )
51 {
52 return 1;
53 }
54
55 result = sumCounter / sumDenominator;
56 return 0;
57}
Base class for feedback objects to be used for cancellation of something running in a worker thread.
Definition: qgsfeedback.h:45
int interpolatePoint(double x, double y, double &result, QgsFeedback *feedback=nullptr) override
Calculates interpolation value for map coordinates x, y.
QgsIDWInterpolator(const QList< QgsInterpolator::LayerData > &layerData)
Constructor for QgsIDWInterpolator, with the specified layerData sources.
Interface class for interpolations.
QVector< QgsInterpolatorVertexData > mCachedBaseData
Cached vertex data for input sources.
bool mDataIsCached
Flag that tells if the cache already has been filled.
Result cacheBaseData(QgsFeedback *feedback=nullptr)
Caches the vertex and value data from the provider.
bool qgsDoubleNear(double a, double b, double epsilon=4 *std::numeric_limits< double >::epsilon())
Compare two doubles (but allow some difference)
Definition: qgis.h:2396
Interpolation data for an individual source vertex.