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qgstotalcurvaturefilter.cpp
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1 /***************************************************************************
2  qgstotalcurvaturefilter.h - description
3  -------------------
4  begin : August 21th, 2009
5  copyright : (C) 2009 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 
19 
20 QgsTotalCurvatureFilter::QgsTotalCurvatureFilter( const QString& inputFile, const QString& outputFile, const QString& outputFormat )
21  : QgsNineCellFilter( inputFile, outputFile, outputFormat )
22 {
23 
24 }
25 
27 {
28 
29 }
30 
31 float QgsTotalCurvatureFilter::processNineCellWindow( float* x11, float* x21, float* x31, float* x12,
32  float* x22, float* x32, float* x13, float* x23, float* x33 )
33 {
34  //return nodata if one value is the nodata value
35  if ( *x11 == mInputNodataValue || *x21 == mInputNodataValue || *x31 == mInputNodataValue || *x12 == mInputNodataValue
36  || *x22 == mInputNodataValue || *x32 == mInputNodataValue || *x13 == mInputNodataValue || *x23 == mInputNodataValue
37  || *x33 == mInputNodataValue )
38  {
39  return mOutputNodataValue;
40  }
41 
42  double cellSizeAvg = ( mCellSizeX + mCellSizeY ) / 2.0;
43  double dxx = ( *x32 - 2 * *x22 + *x12 ) / ( mCellSizeX * mCellSizeX );
44  double dyy = ( -*x11 + *x31 + *x13 - *x33 ) / ( 4 * cellSizeAvg * cellSizeAvg );
45  double dxy = ( *x21 - 2 * *x22 + *x23 ) / ( mCellSizeY * mCellSizeY );
46 
47  return dxx*dxx + 2*dxy*dxy + dyy*dyy;
48 }
QgsTotalCurvatureFilter(const QString &inputFile, const QString &outputFile, const QString &outputFormat)
float processNineCellWindow(float *x11, float *x21, float *x31, float *x12, float *x22, float *x32, float *x13, float *x23, float *x33) override
Calculates total curvature from nine input values.
float mOutputNodataValue
The nodata value of the output layer.
float mInputNodataValue
The nodata value of the input layer.
Base class for raster analysis methods that work with a 3x3 cell filter and calculate the value of ea...