28.2.3. Raster extraction

28.2.3.1. Clip raster by extent

Clips any GDAL-supported raster file to a given extent.

This algorithm is derived from the GDAL translate utility.

Default menu: Raster ► Extraction

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[raster]	The input raster
Clipping extent	EXTENT	[extent]	Extent that should be used for the output raster. Only pixels within the specified bounding box will be included in the output. Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
Override the projection for the output file	OVERCRS	[boolean] Default: False	If checked, the output file is assigned the input layer CRS.
Assign a specified NoData value to output bands Optional	NODATA	[number] Default: None	Defines a value that should be inserted for the NoData values in the output raster
Clipped (extent)	OUTPUT	[raster] Default: [Save to temporary file]	Specification of the output raster layer. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Name	Type	Description
Additional creation options Optional	OPTIONS	[string] Default: ‘’	For adding one or more creation options that control the raster to be created (colors, block size, file compression…). For convenience, you can rely on predefined profiles (see GDAL driver options section). Batch Process and Model Designer: separate multiple options with a pipe character (|).
Output data type	DATA_TYPE	[enumeration] Default: 0	Defines the format of the output raster file. Options: 0 — Use Input Layer Data Type 1 — Byte (Eight bit unsigned integer (quint8)) 2 — Int16 (Sixteen bit signed integer (qint16)) 3 — UInt16 (Sixteen bit unsigned integer (quint16)) 4 — UInt32 (Thirty two bit unsigned integer (quint32)) 5 — Int32 (Thirty two bit signed integer (qint32)) 6 — Float32 (Thirty two bit floating point (float)) 7 — Float64 (Sixty four bit floating point (double)) 8 — CInt16 (Complex Int16) 9 — CInt32 (Complex Int32) 10 — CFloat32 (Complex Float32) 11 — CFloat64 (Complex Float64) 12 — Int8 (Eight bit signed integer (qint8)) Available options depend on the GDAL version built with QGIS (see Help ► About menu)
Additional command-line parameters Optional	EXTRA	[string] Default: None	Add extra GDAL command line options

Outputs

Label	Name	Type	Description
Clipped (extent)	OUTPUT	[raster]	Output raster layer clipped by the given extent

Python code

Algorithm ID: gdal:cliprasterbyextent

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.3.2. Clip raster by mask layer

Clips any GDAL-supported raster by a vector mask layer.

This algorithm is derived from the GDAL warp utility.

Default menu: Raster ► Extraction

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[raster]	The input raster
Mask layer	MASK	[vector: polygon]	Vector mask for clipping the raster
Source CRS	SOURCE_CRS	[crs]	Set the coordinate reference to use for the input raster
Target CRS	TARGET_CRS	[crs]	Set the coordinate reference to use for the mask layer
Target extent Optional	TARGET_EXTENT	[extent]	Extent of the output file to be created Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as xmin, xmax, ymin, ymax
Assign a specified NoData value to output bands Optional	NODATA	[number] Default: None	Defines a value that should be inserted for the NoData values in the output raster
Create an output alpha band	ALPHA_BAND	[boolean] Default: False	Creates an alpha band for the result. The alpha band then includes the transparency values of the pixels.
Match the extent of the clipped raster to the extent of the mask layer	CROP_TO_CUTLINE	[boolean] Default: True	Applies the vector layer extent to the output raster if checked.
Keep resolution of input raster	KEEP_RESOLUTION	[boolean] Default: False	The resolution of the output raster will not be changed
Set output file resolution	SET_RESOLUTION	[boolean] Default: False	Shall the output resolution (cell size) be specified
X Resolution to output bands Optional	X_RESOLUTION	[number] Default: None	The width of the cells in the output raster
Y Resolution to output band Optional	Y_RESOLUTION	[number] Default: None	The height of the cells in the output raster
Use multithreaded warping implementation	MULTITHREADING	[boolean] Default: False	Two threads will be used to process chunks of image and perform input/output operation simultaneously. Note that computation is not multithreaded itself.
Clipped (mask)	OUTPUT	[raster] Default: [Save to temporary file]	Specification of the output raster layer. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Name	Type	Description
Additional creation options Optional	OPTIONS	[string] Default: ‘’	For adding one or more creation options that control the raster to be created (colors, block size, file compression…). For convenience, you can rely on predefined profiles (see GDAL driver options section). Batch Process and Model Designer: separate multiple options with a pipe character (|).
Output data type	DATA_TYPE	[enumeration] Default: 0	Defines the format of the output raster file. Options: 0 — Use Input Layer Data Type 1 — Byte (Eight bit unsigned integer (quint8)) 2 — Int16 (Sixteen bit signed integer (qint16)) 3 — UInt16 (Sixteen bit unsigned integer (quint16)) 4 — UInt32 (Thirty two bit unsigned integer (quint32)) 5 — Int32 (Thirty two bit signed integer (qint32)) 6 — Float32 (Thirty two bit floating point (float)) 7 — Float64 (Sixty four bit floating point (double)) 8 — CInt16 (Complex Int16) 9 — CInt32 (Complex Int32) 10 — CFloat32 (Complex Float32) 11 — CFloat64 (Complex Float64) 12 — Int8 (Eight bit signed integer (qint8)) Available options depend on the GDAL version built with QGIS (see Help ► About menu)
Additional command-line parameters Optional	EXTRA	[string] Default: None	Add extra GDAL command line options

Outputs

Label	Name	Type	Description
Clipped (mask)	OUTPUT	[raster]	Output raster layer clipped by the vector layer

Python code

Algorithm ID: gdal:cliprasterbymasklayer

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.3.3. Contour

Extracts contour lines from any GDAL-supported elevation raster.

This algorithm is derived from the GDAL contour utility.

Default menu: Raster ► Extraction

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[raster]	Input raster
Band number	BAND	[raster band] Default: 1	Raster band to create the contours from
Interval between contour lines	INTERVAL	[number] Default: 10.0	Defines the interval between the contour lines in the given units of the elevation raster (minimum value 0)
Attribute name (if not set, no elevation attribute is attached) Optional	FIELD_NAME	[string] Default: ‘ELEV’	Provides a name for the attribute in which to put the elevation.
Offset from zero relative to which to interpret intervals Optional	OFFSET	[number] Default: 0.0
Contours	OUTPUT	[vector: line] Default: [Save to temporary file]	Specification of the output vector layer. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Name	Type	Description
Produce 3D vector	CREATE_3D	[boolean] Default: False	Forces production of 3D vectors instead of 2D. Includes elevation at every vertex.
Treat all raster values as valid	IGNORE_NODATA	[boolean] Default: False	Ignores any NoData values in the dataset.
Input pixel value to treat as “NoData” Optional	NODATA	[number] Default: None	Defines a value that should be inserted for the NoData values in the output raster
Additional command-line parameters Optional	EXTRA	[string] Default: None	Add extra GDAL command line options. Refer to the corresponding GDAL utility documentation.

Outputs

Label	Name	Type	Description
Contours	OUTPUT	[vector: line]	Output vector layer with contour lines

Python code

Algorithm ID: gdal:contour

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

28.2.3.4. Contour Polygons

Extracts contour polygons from any GDAL-supported elevation raster.

This algorithm is derived from the GDAL contour utility.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[raster]	Input raster
Band number	BAND	[raster band] Default: 1	Raster band to create the contours from
Interval between contour lines	INTERVAL	[number] Default: 10.0	Defines the interval between the contour lines in the given units of the elevation raster (minimum value 0)
Offset from zero relative to which to interpret intervals Optional	OFFSET	[number] Default: 0.0
Attribute name for minimum elevation of contour polygon Optional	FIELD_NAME_MIN	[string] Default: ‘ELEV_MIN’	Provides a name for the attribute in which to put the minimum elevation of contour polygon. If not provided no minimum elevation attribute is attached.
Attribute name for maximum elevation of contour polygon Optional	FIELD_NAME_MAX	[string] Default: ‘ELEV_MAX’	Provides a name for the attribute in which to put the maximum elevation of contour polygon. If not provided no maximum elevation attribute is attached.
Contours	OUTPUT	[vector: polygon] Default: [Save to temporary file]	Specification of the output vector layer. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Name	Type	Description
Produce 3D vector	CREATE_3D	[boolean] Default: False	Forces production of 3D vectors instead of 2D. Includes elevation at every vertex.
Treat all raster values as valid	IGNORE_NODATA	[boolean] Default: False	Ignores any NoData values in the dataset.
Input pixel value to treat as “NoData” Optional	NODATA	[number] Default: None	Defines a value that should be inserted for the NoData values in the output raster
Additional command-line parameters Optional	EXTRA	[string] Default: None	Add extra GDAL command line options. Refer to the corresponding GDAL utility documentation.

Outputs

Label	Name	Type	Description
Contours	OUTPUT	[vector: polygon]	Output vector layer with contour polygons

Python code

Algorithm ID: gdal:contour_polygon

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.