24.2.4. Raster miscellaneous

24.2.4.1. Build overviews (pyramids)

To speed up rendering time of raster layers overviews (pyramids) can be created. Overviews are lower resolution copies of the data which QGIS uses depending of the level of zoom.

This algorithm is derived from the GDAL addo utility.

Default menu: Raster ► Miscellaneous

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layer

INPUT

[raster]

Input raster layer

Remove all existing overviews

CLEAN

[boolean]

Default: False

Removes existing overviews from the raster. By default these are not removed.

Advanced parameters

Label

Nimi

Type

Kuvaus

Overview levels

LEVELS

[string]

Default: ’2 4 8 16’

Defines the number of overview levels calculated by the original resolution of the input raster layer. By default 4 levels will be taken into consideration.

Resampling method

Optional

RESAMPLING

[enumeration]

Default: 0

Calculates the overviews with a defined resampling method. Possible resampling methods are:

  • 0 – Nearest Neighbour (nearest)

  • 1 – Average (average)

  • 2 – Gaussian (gauss)

  • 3 – Cubic Convolution (cubic)

  • 4 – B-Spline Convolution (cubicspline)

  • 5 – Lanczos Windowed Sinc (lanczos)

  • 6 – Average MP (average_mp)

  • 7 – Average in Mag/Phase Space (average_magphase)

  • 8 – Mode (mode)

Overviews format

Optional

FORMAT

[enumeration]

Default: 0

The overviews can be stored internally, or externally as GTiff or ERDAS Imagine file. By default the overviews are stored in the output raster. Possible formats methods are:

  • 0 – Internal (if possible)

  • 1 – External (GTiff .ovr)

  • 2 – External (ERDAS Imagine .aux)

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Pyramidized

OUTPUT

[raster]

Output raster layer with overviews

Python code

Algorithm ID: gdal:overviews

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.

24.2.4.2. Build virtual raster

Builds a VRT (Virtual Dataset) that is a mosaic of the list of input GDAL-supported rasters. With a mosaic you can merge several raster files.

This algorithm is derived from the GDAL buildvrt utility.

Default menu: Raster ► Miscellaneous

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layers

INPUT

[raster] [list]

GDAL-supported raster layers.

Resolution

RESOLUTION

[enumeration]

Default: 0

The output resolution of the mosaic. By default the average resolution of the raster files will be chosen.

Options:

  • 0 — Average (average)

  • 1 — Highest (highest)

  • 2 — Lowest (lowest)

Place each input file into a separate band

SEPARATE

[boolean]

Default: False

With ’True’ you can define that each raster file goes into a separated stacked band in the VRT band.

Allow projection difference

PROJ_DIFFERENCE

[boolean]

Default: False

Allows that the output bands have different projections derived from the projection of the input raster layers.

Virtual

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

Nimi

Type

Kuvaus

Add alpha mask band to VRT when source raster has none

ADD_ALPHA

[boolean]

Default: False

Adds an alpha mask band to the VRT when the source raster has none.

Override projection for the output file

Optional

ASSIGN_CRS

[crs]

Default: None

Overrides the projection for the output file. No reprojection is done.

Resampling algorithm

RESAMPLING

[enumeration]

Default: 0

The resampling algorithm to be used Options:

  • 0 — Nearest Neighbour (nearest)

  • 1 — Bilinear (bilinear)

  • 2 — Cubic Convolution (cubic)

  • 3 — B-Spline Convolution (cubicspline)

  • 4 — Lanczos Windowed Sinc (lanczos)

  • 5 — Average (average)

  • 6 — Mode (mode)

Nodata value(s) for input bands (space separated)

Optional

SRC_NODATA

[string]

Default: None

Space separated Nodata value(s) for input band(s)

Additional command-line parameters

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Virtual

OUTPUT

[raster]

Output raster layer

Python code

Algorithm ID: gdal:buildvirtualraster

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.

24.2.4.3. gdal2tiles

Generates a directory with small tiles and metadata, following the OSGeo Tile Map Service Specification. See also the OpenGIS Web Map Tile Service Implementation Standard. Simple web pages with viewers based on Google Maps, OpenLayers and Leaflet are generated as well. To explore your maps on-line in the web browser, you only need to upload the generated directory onto a web server.

This algorithm also creates the necessary metadata for Google Earth (KML SuperOverlay), in case the supplied map uses EPSG:4326 projection.

ESRI world files and embedded georeferencing is used during tile generation, but you can publish a picture without proper georeferencing too.

This algorithm is derived from the GDAL gdal2tiles utility.

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layer

INPUT

[raster]

GDAL-supported raster layer.

Tile cutting profile

PROFILE

[enumeration]

Default: 0

One of:

  • 0 — Mercator (mercator)

  • 1 — Geodetic (geodetic)

  • 2 — Raster (raster)

Zoom levels to render

Optional

ZOOM

[string]

Default: ’’

Web viewer to generate

VIEWER

[enumerate]

Default: 0

One of:

  • 0 — All (all)

  • 1 — GoogleMaps (google)

  • 2 — OpenLayers (openlayers)

  • 3 — Leaflet (leaflet)

  • 4 — None (none)

Title of the map

Optional

TITLE

[string]

Default: ’’

Copyright of the map

COPYRIGHT

[string]

Default: ’’

Output directory

OUTPUT

[folder]

Default: [Save to temporary folder]

Specify the output folder for the tiles. One of:

  • Save to a Temporary Directory

  • Save to Directory

Advanced parameters

Label

Nimi

Type

Kuvaus

Resampling method

RESAMPLING

[enumeration]

Default: 0

The resampling algorithm to be used Options:

  • 0 — Average (average)

  • 1 — Nearest neighbour (near)

  • 2 — Bilinear (bilinear)

  • 3 — Cubic (cubic)

  • 4 — Cubic spline (cubicspline)

  • 5 — Lanczos Windowed sinc (lanczos)

  • 6 — Antialias (antialias)

The spatial reference system used for the source input data

Optional

SOURCE_CRS

[crs]

Default: None

Transparency value to assign to the input data

Optional

NODATA

[number]

Default: 0.0

URL address where the generated tiles are going to be published

Optional

URL

[string]

Default: ’’

Google Maps API key (http://code.google.com/apis/maps/signup.html)

Optional

GOOGLE_KEY

[string]

Default: ’’

Your Google maps API key.

Bing Maps API key (https://www.bingmapsportal.com/)

Optional

BING_KEY

[string]

Default: ’’

Your Bing maps API key.

Generate only missing files

RESUME

[boolean]

Default: False

Generate KML for Google Earth

KML

[boolean]

Default: False

Avoid automatic generation of KML files for EPSG:4326

NO_KML

[boolean]

Default: False

Tulokset

Label

Nimi

Type

Kuvaus

Output directory

OUTPUT

[folder]

The output folder (for the tiles)

Python code

Algorithm ID: gdal:gdal2tiles

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.

24.2.4.4. Merge

Merges raster files in a simple way. Here you can use a pseudocolor table from an input raster and define the output raster type. All the images must be in the same coordinate system.

This algorithm is derived from the GDAL merge utility.

Default menu: Raster ► Miscellaneous

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layers

INPUT

[raster] [list]

Input raster layers

Grab pseudocolor table from first layer

PCT

[boolean]

Default: False

The pseudocolor table from the first layer will be used for the coloring

Place each input file into a separate band

SEPARATE

[boolean]

Default: False

Place each input file into a separate band

Output data type

DATA_TYPE

[enumeration]

Default: 5

Defines the format of the output raster file. Options:

  • 0 — Byte

  • 1 — Int16

  • 2 — UInt16

  • 3 — UInt32

  • 4 — Int32

  • 5 — Float32

  • 6 — Float64

  • 7 — CInt16

  • 8 — CInt32

  • 9 — CFloat32

  • 10 — CFloat64

Merged

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

Nimi

Type

Kuvaus

Input pixel value to treat as ”nodata”

Optional

NODATA_INPUT

[number]

Default: None

Ignores pixels from files being merged in with this pixel value

Assign specified ”nodata” value to output

Optional

NODATA_OUTPUT

[number]

Default: None

Assigns the specified nodata value to output bands.

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).

For Batch Process: separate multiple options with a pipe character (|).

Additional command-line parameters

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Merged

OUTPUT

[raster]

Output raster layer

Python code

Algorithm ID: gdal:merge

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.

24.2.4.5. Pansharpening

Performs a pan-sharpening operation. It can create a ”classic” output dataset (such as GeoTIFF), or a VRT dataset describing the pan-sharpening operation.

See GDAL Pansharpen.

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Spectral dataset

SPECTRAL

[raster]

Input (spectral) raster layer

Panchromatic dataset

PANCHROMATIC

[raster]

Input (panchromatic) raster layer

Output

OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output (sharpened) raster layer. One of:

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

Resampling algorithm

RESAMPLING

[enumeration]

Default: 2

The resampling algorithm to be used Options:

  • 0 — Nearest Neighbour (nearest)

  • 1 — Bilinear (bilinear)

  • 2 — Cubic (cubic)

  • 3 — Cubic Spline (cubicspline)

  • 4 — Lanczos Windowed Sinc (lanczos)

  • 5 — Average (average)

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).

For Batch Process: separate multiple options with a pipe character (|).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Output

OUTPUT

[raster]

Output (sharpened) raster layer

Python code

Algorithm ID: gdal:pansharp

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.

24.2.4.6. Raster calculator

Command line raster calculator with numpy syntax. Use any basic arithmetic supported by numpy arrays, such as +, -, *, and / along with logical operators, such as >. Note that all input rasters must have the same dimensions, but no projection checking is performed.

See the GDAL Raster Calculator utility docs.

Katso myös

Raster calculator

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layer A

INPUT_A

[raster]

First input raster layer (mandatory)

Number of raster band for A

BAND_A

[raster band]

Band for input layer A (mandatory)

Input layer B

Optional

INPUT_B

[raster]

Default: None

Second input raster layer

Number of raster band for B

Optional

BAND_B

[raster band]

Band for input layer B

Input layer C

Optional

INPUT_C

[raster]

Default: None

Third input raster layer

Number of raster band for C

Optional

BAND_C

[raster band]

Band for input layer C

Input layer D

Optional

INPUT_D

[raster]

Default: None

Fourth input raster layer

Number of raster band for D

Optional

BAND_D

[raster band]

Band for input layer D

Input layer E

Optional

INPUT_E

[raster]

Default: None

Fifth input raster layer

Number of raster band for E

Optional

BAND_E

[raster band]

Band for input layer E

Input layer F

Optional

INPUT_F

[raster]

Sixth input raster layer

Number of raster band for F

Optional

BAND_F

[raster band]

Default: None

Band for input layer F

Calculation in gdalnumeric syntax using +-/* or any numpy array functions (i.e. logical_and())

FORMULA

[string]

Default: ’’

The calculation formula. Examples:

  • A*(A>0) — outputs the value of the raster A if the value of A is greater than 0. If not, outputs 0.

  • A*(A>0 and A>B)— outputs the value of A if that value is bigger than 0 and bigger than the value of B. If not, outputs 0.

  • A*logical_or(A<=177,A>=185) — outputs the value of A if A <= 177 or A >= 185. If not, outputs 0.

  • sqrt(A*A+B*B) — Outputs the square root of the sum of the value of A squared and the value of B squared.

Set output nodata value

Optional

NO_DATA

[number]

Default: None

Value to use for nodata

Output raster type

RTYPE

[enumeration]

Default: 5

Defines the format of the output raster file. Options:

  • 0 — Byte

  • 1 — Int16

  • 2 — UInt16

  • 3 — UInt32

  • 4 — Int32

  • 5 — Float32

  • 6 — Float64

Calculated

OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output (calculated) raster layer. One of:

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

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).

For Batch Process: separate multiple options with a pipe character (|).

Additional command-line parameters

Optional

EXTRA

[string]

Default: ’’

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Calculated

OUTPUT

[raster]

Output (calculated) raster layer

Python code

Algorithm ID: gdal:rastercalculator

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.

24.2.4.7. Raster information

The gdalinfo program lists various information about a GDAL supported raster dataset.

This algorithm is derived from the GDAL info utility.

Default menu: Raster ► Miscellaneous

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layer

INPUT

[raster]

Input raster layer

Force computation of the actual min/max values for each band

MIN_MAX

[boolean]

Default: False

Forces computation of the actual min/max values for each band in the dataset

Read and display image statistics (force computation if necessary)

STATS

[boolean]

Default: False

Reads and displays image statistics. Forces computation if no statistics are stored in an image.

Suppress GCP info

NO_GCP

[boolean]

Default: False

Suppresses ground control points list printing. It may be useful for datasets with huge amount of GCPs, such as L1B AVHRR or HDF4 MODIS which contain thousands of them.

Suppress metadata info

NO_METADATA

[boolean]

Default: False

Suppresses metadata printing. Some datasets may contain a lot of metadata strings.

Layer information

OUTPUT

[html]

Default: [Save to temporary file]

Specify the HTML file for output. One of:

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Layer information

OUTPUT

[html]

The HTML file containing information about the input raster layer

Python code

Algorithm ID: gdal:gdalinfo

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.

24.2.4.8. Retile

Retiles a set of input tiles. All the input tiles must be georeferenced in the same coordinate system and have a matching number of bands. Optionally pyramid levels are generated.

This algorithm is derived from the GDAL Retile utility.

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input files

INPUT

[raster] [list]

The input raster files

Tile width

TILE_SIZE_X

[number]

Default: 256

Width of the tiles in pixels (minimum 0)

Tile height

TILE_SIZE_Y

[number]

Default: 256

Height of the tiles in pixels (minimum 0)

Overlap in pixels between consecutive tiles

OVERLAP

[number]

Default: 0

Number of pyramid levels to build

LEVELS

[number]

Default: 1

Minimum: 0

Output directory

OUTPUT

[folder]

Default: [Save to temporary folder]

Specify the output folder for the tiles. One of:

  • Save to a Temporary Directory

  • Save to Directory

CSV file containing the tile(s) georeferencing information

OUTPUT_CSV

[file]

Default: [Skip output]

Specify the output file for the tiles. One of:

  • Skip Output

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

Source coordinate reference system

Optional

SOURCE_CRS

[crs]

Default: None

Resampling method

RESAMPLING

[enumeration]

Default: 0

The resampling algorithm to be used Options:

  • 0 — Nearest Neighbour (nearest)

  • 1 — Bilinear (bilinear)

  • 2 — Cubic (cubic)

  • 3 — Cubic Spline (cubicspline)

  • 4 — Lanczos Windowed Sinc (lanczos)

Column delimiter used in the CSV file

Optional

DELIMITER

[string]

Default: ’;’

Delimiter to use in the CSV file containing the tile(s) georeferencing information

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).

For Batch Process: separate multiple options with a pipe character (|).

Additional command-line parameters

Optional

EXTRA

[string]

Default: ’’

Add extra GDAL command line options

Output data type

DATA_TYPE

[enumeration]

Default: 5

Defines the format of the output raster file. Options:

  • 0 — Byte

  • 1 — Int16

  • 2 — UInt16

  • 3 — UInt32

  • 4 — Int32

  • 5 — Float32

  • 6 — Float64

  • 7 — CInt16

  • 8 — CInt32

  • 9 — CFloat32

  • 10 — CFloat64

Build only the pyramids

ONLY_PYRAMIDS

[boolean]

Default: False

Use separate directory for each tile row

DIR_FOR_ROW

[boolean]

Default: False

Tulokset

Label

Nimi

Type

Kuvaus

Output directory

OUTPUT

[folder]

The output folder for the tiles.

CSV file containing the tile(s) georeferencing information

OUTPUT_CSV

[file]

The CSV file with georeferencing information for the tiles.

Python code

Algorithm ID: gdal:retile

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.

24.2.4.9. Tile index

Builds a vector layer with a record for each input raster file, an attribute containing the filename, and a polygon geometry outlining the raster. This output is suitable for use with MapServer as a raster tileindex.

This algorithm is derived from the GDAL Tile Index utility.

Default menu: Raster ► Miscellaneous

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input files

LAYERS

[raster] [list]

The input raster files. Can be multiple files.

Field name to hold the file path to the indexed rasters

PATH_FIELD_NAME Optional

[string]

Default: ’location’

The output field name to hold the file path/location to the indexed rasters.

Store absolute path to the indexed rasters

ABSOLUTE_PATH

[boolean]

Default: False

Set whether the absolute path to the raster files is stored in the tile index file. By default the raster filenames will be put in the file exactly as they are specified in the command.

Skip files with different projection reference

PROJ_DIFFERENCE

[boolean]

Default: False

Only files with same projection as files already inserted in the tile index will be inserted. Default does not check projection and accepts all inputs.

Tile index

OUTPUT

[vector: polygon]

Default: [Save to temporary file]

Specify the polygon vector layer to write the index to. One of:

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

Transform geometries to the given CRS

Optional

TARGET_CRS

[crs]

Geometries of input files will be transformed to the specified target coordinate reference system. Default creates simple rectangular polygons in the same coordinate reference system as the input rasters.

The name of the field to store the SRS of each tile

Optional

CRS_FIELD_NAME

[string]

The name of the field to store the SRS of each tile

The format in which the CRS of each tile must be written

CRS_FORMAT

[enumeration]

Default: 0

Format for the CRS. One of:

  • 0 – Auto (AUTO)

  • 1 – Well-known text (WKT)

  • 2 – EPSG (EPSG)

  • 3 – Proj.4 (PROJ)

Tulokset

Label

Nimi

Type

Kuvaus

Tile index

OUTPUT

[vector: polygon]

The polygon vector layer with the tile index.

Python code

Algorithm ID: gdal:tileindex

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.

24.2.4.10. Viewshed

Calculates a viewshed raster from an input raster DEM using method defined in Wang2000 for a user defined point.

Parameters

Basic parameters

Label

Nimi

Type

Kuvaus

Input layer

INPUT

[raster]

Input elevation raster layer

Band number

BAND

[raster band]

Default: 1

The number of the band to use as elevation

Observer location

OBSERVER

[point]

The location of the observer

Observer height

OBSERVER_HEIGHT

[number]

Default: 1.0

The altitude of the observer, in the DEM units

Target height

TARGET_HEIGHT

[number]

Default: 1.0

The altitude of the target element, in the DEM units

Maximum distance from observer to compute visibility

MAX_DISTANCE

[number]

Default: 100.0

Maximum distance from observer to compute visibility, in the DEM units

Output

OUTPUT

[raster]

Default: [Save to temporary file]

Output raster layer. One of:

  • Save to a Temporary File

  • Save to File…

Advanced parameters

Label

Nimi

Type

Kuvaus

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).

For Batch Process: separate multiple options with a pipe character (|).

Additional command-line parameters

EXTRA

[string]

Default: None

Add extra GDAL command line options

Tulokset

Label

Nimi

Type

Kuvaus

Output

OUTPUT

[raster]

The raster layer displaying the viewshed.

Python code

Algorithm ID: gdal:viewshed

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.