Class: QgsAlignRaster¶

QgsAlignRaster takes one or more raster layers and warps (resamples) them so they have the same:

coordinate reference system
cell size and raster size
offset of the raster grid

Enums

ResampleAlg

alias of GdalResampleAlgorithm

Methods

`alignedRasterExtent`	Returns the expected extent of the resulting aligned raster
`alignedRasterSize`	Returns the expected size of the resulting aligned raster
`cellSize`	Gets output cell size
`checkInputParameters`	Determine destination extent from the input rasters and calculate derived values
`clipExtent`	Gets clipping extent (region of interest).
`createAndWarp`	Internal function for processing of one raster (1.
`destinationCrs`	Gets the output CRS in WKT format
`dump`	write contents of the object to standard error stream - for debugging
`errorMessage`	Returns the error from a previous `run()` call.
`gridOffset`
`progressHandler`	Gets associated progress handler.
`rasters`	Gets list of rasters that will be aligned
`run`	Run the alignment process
`setCellSize`	Sets output cell size
`setClipExtent`	Configure clipping extent (region of interest).
`setDestinationCrs`	Sets the output CRS in WKT format
`setGridOffset`
`setParametersFromRaster`	Set destination CRS, cell size and grid offset from a raster file.
`setProgressHandler`	Assign a progress handler instance.
`setRasters`	Sets list of rasters that will be aligned
`suggestedReferenceLayer`	Returns the index of the layer which has smallest cell size (returns -1 on error)

Static Methods

suggestedWarpOutput

Determine suggested output of raster warp to a different CRS.

class qgis.analysis.QgsAlignRaster[source]¶

Bases: object

Item¶: alias of RasterItem

class ProgressHandler¶

Bases: object

Helper struct to be sub-classed for progress reporting

progress(self, complete: float) → bool¶

Method to be overridden for progress reporting.

Parameters:: complete (float) – Overall progress of the alignment operation
Return type:: bool
Returns:: False if the execution should be canceled, True otherwise

class RasterInfo¶

Bases: object

Utility class for gathering information about rasters

bandCount(self) → int¶

Returns the number of raster bands in the file

Return type:: int

cellSize(self) → QSizeF¶

Returns the cell size in map units

Return type:: QSizeF

crs(self) → str¶

Returns the CRS in WKT format

Return type:: str

dump(self)¶: Write contents of the object to standard error stream - for debugging

extent(self) → QgsRectangle¶

Returns the extent of the raster

Return type:: QgsRectangle

gridOffset(self) → QPointF¶

Returns the grid offset

Return type:: QPointF

identify(self, mx: float, my: float) → float¶

Gets raster value at the given coordinates (from the first band)

Parameters:

mx (float)
my (float)

Return type:

float

isValid(self) → bool¶

Check whether the given path is a valid raster

Return type:: bool

origin(self) → QPointF¶

Returns the origin of the raster

Return type:: QPointF

rasterSize(self) → QSize¶

Returns the size of the raster grid in pixels

Return type:: QSize

ResampleAlg¶: alias of GdalResampleAlgorithm

alignedRasterExtent(self) → QgsRectangle[source]¶

Returns the expected extent of the resulting aligned raster

Note

first need to run checkInputParameters() which returns with success

Return type:: QgsRectangle

alignedRasterSize(self) → QSize[source]¶

Returns the expected size of the resulting aligned raster

Note

first need to run checkInputParameters() which returns with success

Return type:: QSize

cellSize(self) → QSizeF[source]¶

Gets output cell size

Return type:: QSizeF

checkInputParameters(self) → bool[source]¶

Determine destination extent from the input rasters and calculate derived values

Return type:: bool
Returns:: True on success, sets error on error (see errorMessage())

clipExtent(self) → QgsRectangle[source]¶

Gets clipping extent (region of interest). No extra clipping is done if the rectangle is null

Return type:: QgsRectangle

createAndWarp(self, raster: QgsAlignRasterData.RasterItem) → bool[source]¶

Internal function for processing of one raster (1. create output, 2. do the alignment)

Parameters:: raster (QgsAlignRasterData.RasterItem)
Return type:: bool

destinationCrs(self) → str[source]¶

Gets the output CRS in WKT format

Return type:: str

dump(self)[source]¶: write contents of the object to standard error stream - for debugging

errorMessage(self) → str[source]¶

Returns the error from a previous run() call. Error message is empty if run() succeeded (returned True)

Return type:: str

gridOffset(self) → QPointF[source]¶

Return type:: QPointF

progressHandler(self) → QgsAlignRaster.ProgressHandler | None[source]¶

Gets associated progress handler. May be None (default)

Return type:: Optional[QgsAlignRaster.ProgressHandler]

rasters(self) → List[QgsAlignRasterData.RasterItem][source]¶

Gets list of rasters that will be aligned

Return type:: List[QgsAlignRasterData.RasterItem]

run(self) → bool[source]¶

Run the alignment process

Return type:: bool
Returns:: True on success, sets error on error (see errorMessage())

setCellSize(self, x: float, y: float)[source]¶

Sets output cell size

Parameters:

x (float)
y (float)

setCellSize(self, size: QSizeF)[source]

Sets output cell size

Parameters:: size (QSizeF)

setClipExtent(self, xmin: float, ymin: float, xmax: float, ymax: float)[source]¶

Configure clipping extent (region of interest). No extra clipping is done if the rectangle is null

Parameters:

xmin (float)
ymin (float)
xmax (float)
ymax (float)

setClipExtent(self, extent: QgsRectangle)[source]

Configure clipping extent (region of interest). No extra clipping is done if the rectangle is null

Parameters:: extent (QgsRectangle)

setDestinationCrs(self, crsWkt: str | None)[source]¶

Sets the output CRS in WKT format

Parameters:: crsWkt (Optional[str])

setGridOffset(self, offset: QPointF | QPoint)[source]¶

Parameters:: offset (Union[QPointF, QPoint])

setParametersFromRaster(self, rasterInfo: QgsAlignRaster.RasterInfo, customCRSWkt: str | None = '', customCellSize: QSizeF = QSizeF(), customGridOffset: QPointF | QPoint = QPointF(-1, -1)) → bool[source]¶

Set destination CRS, cell size and grid offset from a raster file. The user may provide custom values for some of the parameters - in such case only the remaining parameters are calculated.

If default CRS is used, the parameters are set according to the raster file’s geo-transform. If a custom CRS is provided, suggested reprojection is calculated first (using GDAL) in order to determine suitable defaults for cell size and grid offset.

Return type:

bool

Returns:

True on success (may fail if it is not possible to reproject raster to given CRS)

Parameters:

rasterInfo (QgsAlignRaster.RasterInfo)
customCRSWkt (Optional[str] = '')
customCellSize (QSizeF = QSizeF())
customGridOffset (Union[QPointF, QPoint] = QPointF(-1, -1))

setParametersFromRaster(self, filename: str | None, customCRSWkt: str | None = '', customCellSize: QSizeF = QSizeF(), customGridOffset: QPointF | QPoint = QPointF(-1, -1)) → bool[source]

Overridden variant for convenience, taking filename instead RasterInfo object. See the other variant for details.

Parameters:

filename (Optional[str])
customCRSWkt (Optional[str] = '')
customCellSize (QSizeF = QSizeF())
customGridOffset (Union[QPointF, QPoint] = QPointF(-1, -1))

Return type:

bool

setProgressHandler(self, progressHandler: QgsAlignRaster.ProgressHandler | None)[source]¶

Assign a progress handler instance. Does not take ownership. None can be passed.

Parameters:: progressHandler (Optional[QgsAlignRaster.ProgressHandler])

setRasters(self, list: Iterable[QgsAlignRasterData.RasterItem])[source]¶

Sets list of rasters that will be aligned

Parameters:: list (Iterable[QgsAlignRasterData.RasterItem])

suggestedReferenceLayer(self) → int[source]¶

Returns the index of the layer which has smallest cell size (returns -1 on error)

Return type:: int

Determine suggested output of raster warp to a different CRS. Returns True on success

Parameters:

info (QgsAlignRaster.RasterInfo)
destWkt (Optional[str])
cellSize (Optional[QSizeF] = None)
gridOffset (Optional[Union[QPointF, QPoint]] = None)
rect (Optional[QgsRectangle] = None)

Return type:

bool