Adds the ability to calculate derivatives in x- and y-directions. More...

Inheritance diagram for QgsDerivativeFilter:

[legend]

Public Member Functions
	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.

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)

virtual	~QgsNineCellFilter ()=default

double	cellSizeX () const

double	cellSizeY () const

double	inputNodataValue () const

double	outputNodataValue () const

int	processRaster (QgsFeedback *feedback=nullptr)
	Starts the calculation, reads from mInputFile and stores the result in mOutputFile.

void	setCellSizeX (double size)

void	setCellSizeY (double size)

void	setInputNodataValue (double value)

void	setOutputNodataValue (double value)

void	setZFactor (double factor)

double	zFactor () const

Protected Member Functions
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)

Additional Inherited Members
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.

QString	mOutputFile

QString	mOutputFormat

float	mOutputNodataValue = -1.0
	The nodata value of the output layer.

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)

Detailed Description

Adds the ability to calculate derivatives in x- and y-directions.

Needs to be subclassed (e.g. for slope and aspect).

Definition at line 30 of file qgsderivativefilter.h.

Constructor & Destructor Documentation

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

Definition at line 20 of file qgsderivativefilter.cpp.

float QgsDerivativeFilter::calcFirstDerX	(	float *	x11,
		float *	x21,
		float *	x31,
		float *	x12,
		float *	x22,
		float *	x32,
		float *	x13,
		float *	x23,
		float *	x33
	)		const

protected

Calculates the first order derivative in x-direction according to Horn (1981)

Definition at line 26 of file qgsderivativefilter.cpp.

float QgsDerivativeFilter::calcFirstDerY	(	float *	x11,
		float *	x21,
		float *	x31,
		float *	x12,
		float *	x22,
		float *	x32,
		float *	x13,
		float *	x23,
		float *	x33
	)		const

protected

Calculates the first order derivative in y-direction according to Horn (1981)

Definition at line 93 of file qgsderivativefilter.cpp.

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

overridepure virtual

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

x11	surrounding cell top left
x21	surrounding cell central left
x31	surrounding cell bottom left
x12	surrounding cell top central
x22	the central cell for which the value will be calculated
x32	surrounding cell bottom central
x13	surrounding cell top right
x23	surrounding cell central right
x33	surrounding cell bottom right

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

/build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/analysis/raster/qgsderivativefilter.h
/build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/analysis/raster/qgsderivativefilter.cpp