QGIS API Documentation 3.37.0-Master (fdefdf9c27f)
qgsaspectfilter.cpp
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1/***************************************************************************
2 qgsaspectfilter.cpp - description
3 -----------------------------------
4 begin : August 7th, 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
18#include "qgsaspectfilter.h"
19#include <cmath>
20
21QgsAspectFilter::QgsAspectFilter( const QString &inputFile, const QString &outputFile, const QString &outputFormat )
22 : QgsDerivativeFilter( inputFile, outputFile, outputFormat )
23{
24
25}
26
28 float *x11, float *x21, float *x31,
29 float *x12, float *x22, float *x32,
30 float *x13, float *x23, float *x33 )
31{
32 const float derX = calcFirstDerX( x11, x21, x31, x12, x22, x32, x13, x23, x33 );
33 const float derY = calcFirstDerY( x11, x21, x31, x12, x22, x32, x13, x23, x33 );
34
35 if ( derX == mOutputNodataValue ||
36 derY == mOutputNodataValue ||
37 ( derX == 0.0 && derY == 0.0 ) )
38 {
39 return mOutputNodataValue;
40 }
41 else
42 {
43 return 180.0 + std::atan2( derX, derY ) * 180.0 / M_PI;
44 }
45}
46
float processNineCellWindow(float *x11, float *x21, float *x31, float *x12, float *x22, float *x32, float *x13, float *x23, float *x33) override
Calculates output value from nine input values.
QgsAspectFilter(const QString &inputFile, const QString &outputFile, const QString &outputFormat)
Adds the ability to calculate derivatives in x- and y-directions.
float calcFirstDerX(float *x11, float *x21, float *x31, float *x12, float *x22, float *x32, float *x13, float *x23, float *x33) const
Calculates the first order derivative in x-direction according to Horn (1981)
float calcFirstDerY(float *x11, float *x21, float *x31, float *x12, float *x22, float *x32, float *x13, float *x23, float *x33) const
Calculates the first order derivative in y-direction according to Horn (1981)
float mOutputNodataValue
The nodata value of the output layer.