Raster analysis

Aspect

Generates an aspect map from any GDAL-supported elevation raster. Aspect is the compass direction that a slope faces. The pixels will have a value from 0-360° measured in degrees from north indicating the azimuth. On the northern hemisphere, the north side of slopes is often shaded (small azimuth from 0°-90°), while the southern side receives more solar radiation (higher azimuth from 180°-270°).

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Band number BAND

[raster band]

Default: 1

The number of the band to use as elevation
Return trigonometric angle instead of azimuth TRIG_ANGLE

[boolean]

Default: False

Activating the trigonometric angle results in different categories: 0° (East), 90° (North), 180° (West), 270° (South).
Return 0 for flat instead of -9999 ZERO_FLAT

[boolean]

Default: False

Activating this option will insert a 0-value for the value -9999 on flat areas.
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster
Use Zevenbergen&Thorne formula instead of the Horn’s one ZEVENBERGEN

[boolean]

Default: False

Activates Zevenbergen&Thorne formula for smooth landscapes

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Aspect OUTPUT

[raster]

Default: [Save to temporary file]

Output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Aspect OUTPUT [raster] Output raster with angle values in degrees

Color relief

Generates a color relief map from any GDAL-supported elevation raster. Color reliefs can particularly be used to depict elevations. The Algorithm outputs a 4-band raster with values computed from the elevation and a text-based color configuration file. By default, the colors between the given elevation values are blended smoothly and the result is a nice colorized elevation raster.

This algorithm is derived from the GDAL DEM utility .

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Band number BAND

[raster band]

Default: 1

The number of the band to use as elevation
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster
Color configuration file COLOR_TABLE [file] A text-based color configuration file
Matching mode MATCH_MODE

[enumeration]

Default: 2

One of:

  • 0 — Use strict color matching
  • 1 — Use closest RGBA quadruples
  • 2 — Use smoothly blended colours

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Color relief OUTPUT

[raster]

Default: [Save to temporary file]

Output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Color relief OUTPUT [raster] A 4-band output raster

Fill nodata

Fill raster regions with no data values by interpolation from edges. The values for the no-data regions are calculated by the sourrounding pixel values using inverse distance weighting. After the interpolation a smoothing of the results takes placce. Input can be any GDAL-supported raster layer. This algorithm is generally suitable for interpolating missing regions of fairly continuously varying rasters (such as elevation models for instance). It is also suitable for filling small holes and cracks in more irregularly varying images (like airphotos). It is generally not so great for interpolating a raster from sparse point data.

This algorithm is derived from the GDAL fillnodata utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input raster layer
Band number BAND

[raster band]

Default: 1

The band to operate on. Nodata values must be represented by the value 0.
Maximum distance (in pixels) to search out for values to interpolate DISTANCE

[number]

Default: 10

The number of pixels to search in all directions to find values to interpolate from
Number of smoothing iterations to run after the interpolation ITERATIONS

[number]

Default: 0

The number of 3x3 filter passes to run (0 or more) to smoothen the results of the interpolation.
Do not use default validity mask for the input band NO_MASK

[boolean]

Default: False

Activates the user-defined validity mask
Validity mask MASK_LAYER [raster] A raster layer that defines the areas to fill.

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Filled OUTPUT

[raster]

Default: [Save to temporary file]

Specification of the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Filled OUTPUT [raster] Output raster

Grid (Data metrics)

Computes some data metrics using the specified window and output grid geometry.

This algorithm is derived from the GDAL grid utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
Data metric to use METRIC

[enumeration]

Default: 0

One of:

  • 0 — Minimum, minimum value found in grid node search ellipse
  • 1 — Maximum, maximum value found in grid node search ellipse
  • 2 — Range, a difference between the minimum and maximum values found in grid node search ellipse
  • 3 — Count, a number of data points found in grid node search ellipse
  • 4 — Average distance, an average distance between the grid node (center of the search ellipse) and all of the data points found in grid node search ellipse
  • 5 — Average distance between points, an average distance between the data points found in grid node search ellipse. The distance between each pair of points within ellipse is calculated and average of all distances is set as a grid node value
The first radius of search ellipse RADIUS_1

[number]

Default: 0.0

The first radius (X axis if rotation angle is 0) of the search ellipse
The second radius of search ellipse RADIUS_2

[number]

Default: 0.0

The second radius (Y axis if rotation angle is 0) of the search ellipse
Angle of search ellipse rotation in degrees (counter clockwise) ANGLE

[number]

Default: 0.0

Angle of ellipse rotation in degrees. Ellipse rotated counter clockwise.
Minimum number of data points to use MIN_POINTS

[number]

Default: 0.0

Minimum number of data points to average. If less amount of points found the grid node considered empty and will be filled with NODATA marker.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (data metrics) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (data metrics) OUTPUT [raster] Output raster with interpolated values

Grid (IDW with nearest neighbor searching)

Computes the Inverse Distance to a Power gridding combined to the nearest neighbor method. Ideal when a maximum number of data points to use is required.

This algorithm is derived from the GDAL grid utility .

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
Weighting power POWER

[number]

Default: 2.0

Weighting power
Smoothing SMOOTHING

[number]

Default: 0.0

Smoothing parameter
The radius of the search circle RADIUS

[number]

Default: 1.0

The radius of the search circle
Maximum number of data points to use MAX_POINTS

[number]

Default: 12

Do not search for more points than this number.
Minimum number of data points to use MIN_POINTS

[number]

Default: 0

Minimum number of data points to average. If less amount of points found the grid node considered empty and will be filled with NODATA marker.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (IDW with NN search) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (IDW with NN search) OUTPUT [raster] Output raster with interpolated values

Grid (Inverse distance to a power)

The Inverse Distance to a Power gridding method is a weighted average interpolator.

You should supply the input arrays with the scattered data values including coordinates of every data point and output grid geometry. The function will compute interpolated value for the given position in output grid.

This algorithm is derived from the GDAL grid utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
Weighting power POWER

[number]

Default: 2.0

Weighting power
Smothing SMOOTHING

[number]

Default: 0.0

Smoothing parameter
The first radius of search ellipse RADIUS_1

[number]

Default: 0.0

The first radius (X axis if rotation angle is 0) of the search ellipse
The second radius of search ellipse RADIUS_2

[number]

Default: 0.0

The second radius (Y axis if rotation angle is 0) of the search ellipse
Angle of search ellipse rotation in degrees (counter clockwise) ANGLE

[number]

Default: 0.0

Angle of ellipse rotation in degrees. Ellipse rotated counter clockwise.
Maximum number of data points to use MAX_POINTS

[number]

Default: 0

Do not search for more points than this number.
Minimum number of data points to use MIN_POINTS

[number]

Default: 0

Minimum number of data points to average. If less amount of points found the grid node considered empty and will be filled with NODATA marker.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (IDW) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (IDW) OUTPUT [raster] Output raster with interpolated values

Grid (Linear)

The Linear method perform linear interpolation by computing a Delaunay triangulation of the point cloud, finding in which triangle of the triangulation the point is, and by doing linear interpolation from its barycentric coordinates within the triangle. If the point is not in any triangle, depending on the radius, the algorithm will use the value of the nearest point or the NODATA value.

This algorithm is derived from the GDAL grid utility .

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
Search distance RADIUS

[number]

Default: -1.0

In case the point to be interpolated does not fit into a triangle of the Delaunay triangulation, use that maximum distance to search a nearest neighbour, or use nodata otherwise. If set to -1, the search distance is infinite. If set to 0, no data value will be used.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (Linear) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (Linear) OUTPUT [raster] Output raster with interpolated values

Grid (Moving average)

The Moving Average is a simple data averaging algorithm. It uses a moving window of elliptic form to search values and averages all data points within the window. Search ellipse can be rotated by specified angle, the center of ellipse located at the grid node. Also the minimum number of data points to average can be set, if there are not enough points in window, the grid node considered empty and will be filled with specified NODATA value.

This algorithm is derived from the GDAL grid utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
The first radius of search ellipse RADIUS_1

[number]

Default: 0.0

The first radius (X axis if rotation angle is 0) of the search ellipse
The second radius of search ellipse RADIUS_2

[number]

Default: 0.0

The second radius (Y axis if rotation angle is 0) of the search ellipse
Angle of search ellipse rotation in degrees (counter clockwise) ANGLE

[number]

Default: 0.0

Angle of ellipse rotation in degrees. Ellipse rotated counter clockwise.
Minimum number of data points to use MIN_POINTS

[number]

Default: 0.0

Minimum number of data points to average. If less amount of points found the grid node considered empty and will be filled with NODATA marker.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (moving average) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (moving average) OUTPUT [raster] Output raster with interpolated values

Grid (Nearest neighbor)

The Nearest Neighbor method doesn’t perform any interpolation or smoothing, it just takes the value of nearest point found in grid node search ellipse and returns it as a result. If there are no points found, the specified NODATA value will be returned.

This algorithm is derived from the GDAL grid utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Point layer INPUT [vector: point] Input point vector layer
The first radius of search ellipse RADIUS_1

[number]

Default: 0.0

The first radius (X axis if rotation angle is 0) of the search ellipse
The second radius of search ellipse RADIUS_2

[number]

Default: 0.0

The second radius (Y axis if rotation angle is 0) of the search ellipse
Angle of search ellipse rotation in degrees (counter clockwise) ANGLE

[number]

Default: 0.0

Angle of ellipse rotation in degrees. Ellipse rotated counter clockwise.
Nodata NODATA

[number]

Default: 0.0

No data marker to fill empty points

Z value from field

Optional

Z_FIELD [tablefield: numeric] Field for the interpolation

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Interpolated (Nearest neighbour) OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Interpolated (Nearest neighbour) OUTPUT [raster] Output raster with interpolated values

Hillshade

Outputs a raster with a nice shaded relief effect. It’s very useful for visualizing the terrain. You can optionally specify the azimuth and altitude of the light source, a vertical exaggeration factor and a scaling factor to account for differences between vertical and horizontal units.

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input Elevation raster layer
Band number BAND

[raster band]

Default: 1

Band containing the elevation information
Z factor (vertical exaggeration) Z_FACTOR

[number]

Default: 1.0

The factor exaggerates the height of the output elevation raster
Scale (ratio of vert. units to horiz.) SCALE

[number]

Default: 1.0

The ratio of vertical units to horizontal units
Azimuth of the light AZIMUTH

[number]

Default: 315.0

Defines the azimuth of the light shining on the elevation raster in degrees. If it comes from the top of the raster the value is 0, if it comes from the east it is 90 a.s.o.
Altitude of the light ALTITUDE

[number]

Default: 45.0

Defines the altitude of the light, in degrees. 90 if the light comes from above the elevation raster, 0 if it is raking light.
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster
Use Zevenbergen&Thorne formula (instead of the Horn’s one) ZEVENBERGEN

[boolean]

Default: False

Activates Zevenbergen&Thorne formula for smooth landscapes
Combined shading COMBINED

[boolean]

Default: False

 
Multidirectional shading MULTIDIRECTIONAL

[boolean]

Default: False

 

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Hillshade OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer with interpolated values. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Hillshade OUTPUT [raster] Output raster with interpolated values

Near black

Converts nearly black/white borders to black.

This algorithm will scan an image and try to set all pixels that are nearly or exactly black, white or one or more custom colors around the collar to black or white. This is often used to “fix up” lossy compressed airphotos so that color pixels can be treated as transparent when mosaicking.

This algorithm is derived from the GDAL nearblack utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input Elevation raster layer
How far from black (white) NEAR

[number]

Default: 15

Select how far from black, white or custom colors the pixel values can be and still considered near black, white or custom color.
Search for nearly white pixels instead of nearly black WHITE

[boolean]

Default: False

Search for nearly white (255) pixels instead of nearly black pixels

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Nearblack OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Nearblack OUTPUT [raster] Output raster

Proximity (raster distance)

Generates a raster proximity map indicating the distance from the center of each pixel to the center of the nearest pixel identified as a target pixel. Target pixels are those in the source raster for which the raster pixel value is in the set of target pixel values.

This algorithm is derived from the GDAL proximity utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input Elevation raster layer
Band number BAND

[raster band]

Default: 1

Band containing the elevation information

A list of pixel values in the source image to be considered target pixels

Optional

VALUES

[string]

Default: ‘’

A list of target pixel values in the source image to be considered target pixels. If not specified, all non-zero pixels will be considered target pixels.
Distance units UNITS

[enumeration]

Default: 1

Indicate whether distances generated should be in pixel or georeferenced coordinates. One of:

  • 0 — Georeferenced coordinates
  • 1 — Pixel coordinates

The maximum distance to be generated

Optional

MAX_DISTANCE

[number]

Default: 0.0

The maximum distance to be generated. The nodata value will be used for pixels beyond this distance. If a nodata value is not provided, the output band will be queried for its nodata value. If the output band does not have a nodata value, then the value 65535 will be used. Distance is interpreted according to the value of Distance units.

Value to be applied to all pixels that are within the maxdist of target pixels

Optional

REPLACE

[number]

Default: 0.0

Specify a value to be applied to all pixels that are closer than the maximum distance from target pixels (including the target pixels) instead of a distance value.

Nodata value to use for the destination proximity raster

Optional

NODATA

[number]

Default: 0.0

Specify the nodata value to use for the output raster

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Output data type DATA_TYPE

[enumeration]

Default: 5

Defines the data type 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
Proximity map OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Proximity map OUTPUT [raster] Output raster

Roughness

Outputs a single-band raster with values computed from the elevation. Roughness is the degree of irregularity of the surface. It’s calculated by the largest inter-cell difference of a central pixel and its surrounding cell. The determination of the roughness plays a role in the analysis of terrain elevation data, it’s useful for calculations of the river morphology, in climatology and physical geography in general.

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Band number BAND

[raster band]

Default: 1

The number of the band to use as elevation
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster

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).
Roughness OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Roughness OUTPUT [raster] Single-band output roughness raster. The value -9999 is used as nodata value.

Sieve

Removes raster polygons smaller than a provided threshold size (in pixels) and replaces them with the pixel value of the largest neighbour polygon. It is useful if you have a large amount of small areas on your raster map.

This algorithm is derived from the GDAL sieve utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Threshold THRESHOLD

[number]

Default: 10

Only raster polygons smaller than this size will be removed
Use 8-connectedness EIGHT_CONNECTEDNESS

[boolean]

Default: False

Use eight connectedness instead of four connectedness
Do not use the default validity mask for the input band NO_MASK

[boolean]

Default: False

 

Validity mask

Optional

MASK_LAYER [raster] Validity mask to use instead of the default

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Sieved OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Sieved OUTPUT [raster] Output raster layer.

Slope

Generates a slope map from any GDAL-supported elevation raster. Slope is the angle of inclination to the horizontal. You have the option of specifying the type of slope value you want: degrees or percent slope.

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input Elevation raster layer
Band number BAND

[raster band]

Default: 1

Band containing the elevation information
Ratio of vertical units to horizontal SCALE

[number]

Default: 1.0

The ratio of vertical units to horizontal units
Slope expressed as percent (instead of degrees) AS_PERCENT

[boolean]

Default: False

Express slope as percent instead of degrees
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster
Use Zevenbergen&Thorne formula (instead of the Horn’s one) ZEVENBERGEN

[boolean]

Default: False

Activates Zevenbergen&Thorne formula for smooth landscapes

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).

Additional command-line parameters

Optional

EXTRA

[string]

Default: None

Add extra GDAL command line options
Slope OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Slope OUTPUT [raster] Output raster

Terrain Ruggedness Index (TRI)

Outputs a single-band raster with values computed from the elevation. TRI stands for Terrain Ruggedness Index, which is defined as the mean difference between a central pixel and its surrounding cells.

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Band number BAND

[raster band]

Default: 1

The number of the band to use as elevation
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster

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).
Terrain Ruggedness Index OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Terrain Ruggedness Index OUTPUT [raster] Output ruggedness raster. The value -9999 is used as nodata value.

Topographic Position Index (TPI)

Outputs a single-band raster with values computed from the elevation. TPI stands for Topographic Position Index, which is defined as the difference between a central pixel and the mean of its surrounding cells.

This algorithm is derived from the GDAL DEM utility .

Default menu: Raster ‣ Analysis

Parameters

Label Name Type Description
Input layer INPUT [raster] Input elevation raster layer
Band number BAND

[raster band]

Default: 1

The number of the band to use for elevation values
Compute edges COMPUTE_EDGES

[boolean]

Default: False

Generates edges from the elevation raster

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).
Terrain Ruggedness Index OUTPUT

[raster]

Default: [Save to temporary file]

Specify the output raster layer. One of:

  • Save to a Temporary File
  • Save to File…

The file encoding can also be changed here.

Outputs

Label Name Type Description
Terrain Ruggedness Index OUTPUT [raster] Output raster.