Class: QgsAlignRaster

Takes one or more raster layers and warps (resamples) them to a common grid.

The aligned rasters will have the same:

  • coordinate reference system

  • cell size and raster size

  • offset of the raster grid

Note

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

The following methods must be implemented: progress()

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

setCellSize(self, size: QSizeF) Sets output cell size

Parameters:

  • x (float)

  • y (float)

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

setClipExtent(self, extent: QgsRectangle) 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)

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)

setParametersFromRaster(self, filename: Optional[str], customCRSWkt: Optional[str] = ‘’, customCellSize: QSizeF = QSizeF(), customGridOffset: Union[QPointF, QPoint] = QPointF(-1, -1)) -> bool Overridden variant for convenience, taking filename instead RasterInfo object. See the other variant for details.

Parameters:

  • rasterInfo (QgsAlignRaster.RasterInfo)

  • customCRSWkt (Optional[str] = '')

  • customCellSize (QSizeF = QSizeF())

  • customGridOffset (Union[QPointF, QPoint] = QPointF(-1, -1))

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

static suggestedWarpOutput(info: QgsAlignRaster.RasterInfo, destWkt: str | None, cellSize: QSizeF | None = None, gridOffset: QPointF | QPoint | None = None, rect: QgsRectangle | None = None) → bool[source]

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

Parameters:
Return type:

bool