Class: QgsNineCellFilter

class qgis.analysis.QgsNineCellFilter(inputFile: str, outputFile: str, outputFormat: str)

Bases: sip.wrapper

Constructor that takes input file, output file and output format (GDAL string)

QgsNineCellFilter(QgsNineCellFilter)

Base class for raster analysis methods that work with a 3x3 cell filter and calculate the value of each cell based on the cell value and the eight neighbour cells. Common examples are slope and aspect calculation in DEMs. Subclasses only implement the method that calculates the new value from the nine values. Everything else (reading file, writing file) is done by this subclass*

Enums

Methods

cellSizeX
cellSizeY
inputNodataValue
outputNodataValue
processNineCellWindow	Calculates output value from nine input values.
processRaster	Starts the calculation, reads from mInputFile and stores the result in mOutputFile
setCellSizeX
setCellSizeY
setInputNodataValue
setOutputNodataValue
setZFactor
zFactor

Signals

Attributes

cellSizeX(self) → float

cellSizeY(self) → float

inputNodataValue(self) → float

outputNodataValue(self) → float

processNineCellWindow(self) → Tuple[float, float, float, float, float, float, float, float, float, float]

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

Returns

the calculated cell value for the central cell x22

processRaster(self, feedback: QgsFeedback = None) → int

Starts the calculation, reads from mInputFile and stores the result in mOutputFile

Parameters

feedback – feedback object that receives update and that is checked for cancellation.

Returns

0 in case of success

setCellSizeX(self, size: float)

setCellSizeY(self, size: float)

setInputNodataValue(self, value: float)

setOutputNodataValue(self, value: float)

setZFactor(self, factor: float)

zFactor(self) → float