QGIS API Documentation 3.27.0-Master (75dc696944)
Public Member Functions | List of all members
QgsAspectFilter Class Reference

Calculates aspect values in a window of 3x3 cells based on first order derivatives in x- and y- directions. More...

#include <qgsaspectfilter.h>

Inheritance diagram for QgsAspectFilter:
Inheritance graph
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Public Member Functions

 QgsAspectFilter (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 output value from nine input values. More...
 
- Public Member Functions inherited from QgsDerivativeFilter
 QgsDerivativeFilter (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=0
 Calculates output value from nine input values. More...
 
- Public Member Functions inherited from QgsNineCellFilter
 QgsNineCellFilter (const QString &inputFile, const QString &outputFile, const QString &outputFormat)
 Constructor that takes input file, output file and output format (GDAL string) More...
 
virtual ~QgsNineCellFilter ()=default
 
double cellSizeX () const
 
double cellSizeY () const
 
double inputNodataValue () const
 
double outputNodataValue () const
 
virtual float processNineCellWindow (float *x11, float *x21, float *x31, float *x12, float *x22, float *x32, float *x13, float *x23, float *x33)=0
 Calculates output value from nine input values. More...
 
int processRaster (QgsFeedback *feedback=nullptr)
 Starts the calculation, reads from mInputFile and stores the result in mOutputFile. More...
 
void setCellSizeX (double size)
 
void setCellSizeY (double size)
 
void setInputNodataValue (double value)
 
void setOutputNodataValue (double value)
 
void setZFactor (double factor)
 
double zFactor () const
 

Additional Inherited Members

- Protected Member Functions inherited from QgsDerivativeFilter
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) More...
 
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) More...
 
- Protected Attributes inherited from QgsNineCellFilter
double mCellSizeX = -1.0
 
double mCellSizeY = -1.0
 
QString mInputFile
 
float mInputNodataValue = -1.0
 The nodata value of the input layer. More...
 
QString mOutputFile
 
QString mOutputFormat
 
float mOutputNodataValue = -1.0
 The nodata value of the output layer. More...
 
double mZFactor = 1.0
 Scale factor for z-value if x-/y- units are different to z-units (111120 for degree->meters and 370400 for degree->feet) More...
 

Detailed Description

Calculates aspect values in a window of 3x3 cells based on first order derivatives in x- and y- directions.

Direction is clockwise starting from north.

Definition at line 30 of file qgsaspectfilter.h.

Constructor & Destructor Documentation

◆ QgsAspectFilter()

QgsAspectFilter::QgsAspectFilter ( const QString &  inputFile,
const QString &  outputFile,
const QString &  outputFormat 
)

Definition at line 21 of file qgsaspectfilter.cpp.

Member Function Documentation

◆ processNineCellWindow()

float QgsAspectFilter::processNineCellWindow ( float *  x11,
float *  x21,
float *  x31,
float *  x12,
float *  x22,
float *  x32,
float *  x13,
float *  x23,
float *  x33 
)
overridevirtual

Calculates output value from nine input values.

The input values and the output value can be equal to the nodata value if not present or outside of the border. Must be implemented by subclasses.

First index of the input cell is the row, second index is the column

Parameters
x11surrounding cell top left
x21surrounding cell central left
x31surrounding cell bottom left
x12surrounding cell top central
x22the central cell for which the value will be calculated
x32surrounding cell bottom central
x13surrounding cell top right
x23surrounding cell central right
x33surrounding cell bottom right
Returns
the calculated cell value for the central cell x22

Implements QgsDerivativeFilter.

Definition at line 27 of file qgsaspectfilter.cpp.


The documentation for this class was generated from the following files: