Class: 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

Note

This is an abstract class, with methods which must be implemented by a subclass.

The following methods must be implemented: processNineCellWindow()

Class Hierarchy¶

Subclasses¶

`QgsDerivativeFilter`	Adds the ability to calculate derivatives in x- and y-directions.
`QgsRuggednessFilter`	Calculates the ruggedness index based on a 3x3 moving window.
`QgsTotalCurvatureFilter`	Calculates total curvature as described by Wilson, Gallant (2000): terrain analysis.

Enums

Result

Abstract Methods

processNineCellWindow

Calculates output value from nine input values.

Methods

`cellSizeX`
`cellSizeY`
`creationOptions`	Returns the list of data source creation options which will be used when creating the output raster file.
`inputNodataValue`
`outputNodataValue`
`processRaster`	Starts the calculation, reads from mInputFile and stores the result in mOutputFile
`setCellSizeX`
`setCellSizeY`
`setCreationOptions`	Sets a list of data source creation options to use when creating the output raster file.
`setInputNodataValue`
`setOutputNodataValue`
`setZFactor`
`zFactor`

class qgis.analysis.QgsNineCellFilter[source]¶

Bases: object

__init__(inputFile: str | None, outputFile: str | None, outputFormat: str | None)

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

Parameters:

inputFile (Optional[str])
outputFile (Optional[str])
outputFormat (Optional[str])

__init__(a0: QgsNineCellFilter)

Parameters:: a0 (QgsNineCellFilter)

class Result(*values)¶

Bases: IntEnum

Added in version 3.44.

Success: Operation completed successfully
InputLayerError: Error reading input file
DriverError: Could not open the driver for the specified format
CreateOutputError: Error creating output file
InputBandError: Error reading input raster band
OutputBandError: Error reading output raster band
RasterSizeError: Raster height is too small (need at least 3 rows)
Canceled: User canceled calculation

Canceled = 7¶

CreateOutputError = 3¶

DriverError = 2¶

InputBandError = 4¶

InputLayerError = 1¶

OutputBandError = 5¶

RasterSizeError = 6¶

Success = 0¶

cellSizeX(self) → float[source]¶

Return type:: float

cellSizeY(self) → float[source]¶

Return type:: float

creationOptions(self) → List[str][source]¶

Returns the list of data source creation options which will be used when creating the output raster file.