ラスタ分析

ラスタ計算機

ラスタレイヤを使用して代数演算を実行します。

結果のレイヤは、式に従って計算された値になります。式には、数値、演算子、現在のプロジェクト内の任意のレイヤへの参照を含めることができます。

注釈

バッチ処理インターフェイス または QGIS Python コンソール から計算機を使用するときは、使用するファイルを指定する必要があります。対応するレイヤは、ファイルのベース名を使用して参照されます（フルパスなし）。例えば、 path/to/my/rasterfile.tif にあるレイヤーを使用している場合、そのレイヤーの最初のバンドは rasterfile.tif@1 として参照されます。

Parameters

Label

Name

Type

Description

Layers

GUI only

Shows the list of all raster layers loaded in the legend. These can be used to fill the expression box (double click to add). Raster layers are referred by their name and the number of the band: layer_name@band_number. For instance, the first band from a layer named DEM will be referred as DEM@1.

Operators

GUI only

Contains some calculator like buttons that can be used to fill the expression box.

Expression

EXPRESSION

[string]

出力ラスタレイヤの計算に使用される式。このボックスに式を直接入力するために提供されている演算子ボタンを使用できます。

Predefined expressions

GUI only

You can use the predefined NDVI expression or you can define new expressions for calculations. The Add... button loads a defined expression (and lets you set the parameters). The Save... button lets you define a new expression.

Reference layer(s) (used for automated extent, cellsize, and CRS)

Optional

LAYERS

[raster] [list]

Layer(s) that will be used to fetch extent, cell size and CRS. By choosing the layer in this box you avoid filling in all the other parameters by hand. Raster layers are referred by their name and the number of the band: layer_name@band_number. For instance, the first band from a layer named DEM will be referred as DEM@1.

Cell size (use 0 or empty to set it automatically)

Optional

CELLSIZE

[number]

Cell size of the output raster layer. If the cell size is not specified, the minimum cell size of the selected reference layer(s) will be used. The cell size will be the same for the X and Y axes.

Output extent (xmin, xmax, ymin, ymax)

EXTENT

[extent]

Extent of the output raster layer. If the extent is not specified, the minimum extent that covers all the selected reference layers will be used.

Output CRS

Optional

CRS

[crs]

CRS of the output raster layer. If the output CRS is not specified, the CRS of the first reference layer will be used.

Output

OUTPUT

[raster]

Default: [Save to temporary file]

Specification of the output raster. One of:

  • Save to a Temporary File

  • Save to File...

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Output

OUTPUT

[raster]

Output raster file with the calculated values.

Raster layer statistics

Calculates basic statistics from the values in a given band of the raster layer. The output is loaded in the Processing ‣ Results viewer menu.

Parameters

Label

Name

Type

Description

Input layer

INPUT

[raster]

Input raster layer

Band number

BAND

[raster band]

Default: The first band of the input layer

If the raster is multiband, choose the band you want to get statistics for.

Output

OUTPUT_HTML_FILE

[html]

Default: [Save to temporary file]

Specification of the output file:

  • Skip Output

  • Save to a Temporary File

  • Save to File...

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Maximum value

MAX

[number]

Mean value

MEAN

[number]

Minimum value

MIN

[number]

Output

OUTPUT_HTML_FILE

[html]

The output file contains the following information:

  • Analyzed file: path of the raster layer

  • Minimum value: minimum value of the raster

  • Maximum value: maximum value of the raster

  • Range: difference between the maximum and minimum values

  • Sum: total sum of the values

  • Mean value: mean of the values

  • Standard deviation: standard deviation of the values

  • Sum of the squares: sum of the squared differences of each observation from the overall mean

Range

RANGE

[number]

Standard deviation

STD_DEV

[number]

Sum

SUM

[number]

Sum of the squares

SUM_OF_SQUARES

[number]

Raster layer unique values report

Returns the count and area of each unique value in a given raster layer.

Parameters

Label

Name

Type

Description

Input layer

INPUT

[raster]

Input raster layer

Band number

BAND

[raster band]

Default: The first band of the input layer

If the raster is multiband, choose the band you want to get statistics for.

Unique values report

OUTPUT_HTML_FILE

[file]

Default: [Save to temporary file]

Specification of the output file:

  • Skip Output

  • Save to a Temporary File

  • Save to File...

The file encoding can also be changed here.

Unique values table

OUTPUT_TABLE

[table]

Default: [Skip output]

Specification of the table for unique values:

  • Skip Output

  • Create Temporary Layer

  • Save to File...

  • Save to GeoPackage...

  • Save to PostGIS Table...

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

CRS authority identifier

CRS_AUTHID

[crs]

Extent

EXTENT

[extent]

Height in pixels

HEIGHT_IN_PIXELS

[number]

NODATA pixel count

NODATA_PIXEL_COUNT

[number]

Total pixel count

TOTAL_PIXEL_COUNT

[number]

Unique values report

OUTPUT_HTML_FILE

[html]

The output HTML file contains the following information:

  • Analyzed file: the path of the raster layer

  • Extent: xmin, ymin, xmax, ymax coordinates of the extent

  • Projection: projection of the layer

  • Width in pixels: number of columns and pixel width size

  • Height in pixels: number of rows and pixel width size

  • Total pixel count: count of all the pixels

  • NODATA pixel count: count of pixels with NODATA value

Unique values table

OUTPUT_TABLE

[table]

A table with three columns:

  • value: pixel value

  • count: count of pixels with this value

  • m2: total area in square meters of pixels with this value.

Width in pixels

WIDTH_IN_PIXELS

[number]

Reclassify by layer

Reclassifies a raster band by assigning new class values based on the ranges specified in a vector table.

Parameters

Label

Name

Type

Description

Raster layer

INPUT_RASTER

[raster]

Raster layer to reclassify

Band number

RASTER_BAND

[raster band]

Default: The first band of the raster layer

If the raster is multiband, choose the band you want to reclassify.

Layer containing class breaks

INPUT_TABLE

[vector: any]

Vector layer containing the values to use for classification.

Minimum class value field

MIN_FIELD

[tablefield: numeric]

Field with the minimum value of the range for the class.

Maximum class value field

MAX_FIELD

[tablefield: numeric]

Field with the maximum value of the range for the class.

Output value field

VALUE_FIELD

[tablefield: numeric]

Field with the value that will be assigned to the pixels that fall in the class (between the corresponding min and max values).

Output no data value

NO_DATA

[number]

Default: -9999.0

Value to apply to no data values.

Range boundaries

RANGE_BOUNDARIES

[enumeration]

Default: 0

Defines comparison rules for the classification. Options:

  • 0 --- min < value <= max

  • 1 --- min <= value < max

  • 2 --- min <= value <= max

  • 3 --- min < value < max

Use no data when no range matches value

NODATA_FOR_MISSING

[boolean]

Default: False

Values that do not belong to a class will result in the no data value. If False, the original value is kept.

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

Reclassified raster

OUTPUT

[raster]

Specification of the output raster. One of:

  • Save to a Temporary File

  • Save to File...

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Reclassified raster

OUTPUT

[raster]

Output raster layer with reclassified band values

Reclassify by table

Reclassifies a raster band by assigning new class values based on the ranges specified in a fixed table.

Parameters

Label

Name

Type

Description

Raster layer

INPUT_RASTER

[raster]

Raster layer to reclassify

Band number

RASTER_BAND

[raster band]

Default: The first band of the raster layer

If the raster is multiband, choose the band you want to reclassify.

Reclassification table

TABLE

[matrix]

A 3-columns table (formatted as a list of nine numbers) containing the values to use for class boundaries (Minimum and Maximum) and the new Value to assign to the band values that fall in the class.

Output no data value

NO_DATA

[number]

Default: -9999.0

Value to use for nodata in the output

Range boundaries

RANGE_BOUNDARIES

[enumeration]

Default: 0

Defines comparison rules for the classification. Options:

  • 0 --- min < value <= max

  • 1 --- min <= value < max

  • 2 --- min <= value <= max

  • 3 --- min < value < max

Use no data when no range matches value

NODATA_FOR_MISSING

[boolean]

Default: False

Values that do not belong to a class will result in the no data value. If False, the original value is kept.

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

Reclassified raster

OUTPUT

[raster]

Specification of the output raster. One of:

  • Save to a Temporary File

  • Save to File...

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Reclassified raster

OUTPUT

[raster]

Output raster layer with reclassified band values

Sample raster values

Extracts raster values at the point locations. If the raster layer is multiband, each band is sampled.

The attribute table of the resulting layer will have as many new columns as there are bands in the raster layer.

Parameters

Label

Name

Type

Description

Input Point Layer

INPUT

[vector: point]

Point vector layer in input to use for the sampling.

Raster Layer to sample

RASTERCOPY

[raster]

Raster layer to sample at input point layer locations.

Output column prefix

COLUMN_PREFIX

[string]

Default: 'rvalue'

Prefix for the column(s) name.

Sampled Points

OUTPUT

[vector: point]

Default: [Create temporary layer]

Specify the output point vector layer for the sampled raster values. One of:

  • Create Temporary Layer (TEMPORARY_OUTPUT)

  • Save to File...

  • Save to Geopackage...

  • Save to PostGIS Table

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Sampled Points

OUTPUT

[vector: point]

Output point vector layer with additional column(s) containing the sampled raster values.

Zonal histogram

Appends fields representing counts of each unique value from a raster layer contained within zones defined as polygons.

The output layer attribute table will have as many fields as the unique values of the raster layer that intersects the polygon(s).

../../../../_images/raster_histogram.png

Raster layer histogram example

Parameters

Label

Name

Type

Description

Raster layer

INPUT_RASTER

[raster]

Input raster layer

Band number

RASTER_BAND

[raster band]

Default: The first band raster layer to sample

If the raster is multiband, choose the band to use for the zonal histogram.

Vector layer containing the zones

INPUT_VECTOR

[vector: polygon]

Polygon vector layer that defines the zones.

Output column prefix

Optional

COLUMN_PREFIX

[string]

Default: 'HISTO_'

Prefix for output column name(s).

Output zones

OUTPUT

[vector: polygon]

Default: [Create temporary layer]

Specify the output polygon vector layer with count of raster values. One of:

  • Create Temporary Layer (TEMPORARY_OUTPUT)

  • Save to File...

  • Save to Geopackage...

  • Save to PostGIS Table

The file encoding can also be changed here.

Outputs

Label

Name

Type

Description

Output zones

OUTPUT

[vector: polygon]

Output polygon vector layer with count of raster values.

Zonal statistics

重なっているポリゴンベクタレイヤの各地物についてラスタレイヤの統計を計算します。

警告

No new output file will be created. The algorithm adds new columns to the input vector layer.

Parameters

Label

Name

Type

Description

Raster Layer

INPUT_RASTER

[raster]

Input raster layer

Band number

RASTER_BAND

[raster band]

Default: The first band of the raster layer

If the raster is multiband, choose the band to use for the zonal histogram.

Vector layer containing the zones

INPUT_VECTOR

[vector: polygon]

Pologyn vector layer that defines the zones (and that will be updated with new statistics columns).

Output column prefix

Optional

COLUMN_PREFIX

[string]

Default: '_'

Prefix for the output column name(s).

Statistics to calculate

STATS

[enumeration] [list]

Default: [0 1 2]

List of statistical operators for the output. The available operators are:

  • 0 -- Count

  • 1 -- Sum

  • 2 -- Mean

  • 3 -- Median

  • 4 -- St. dev.

  • 5 -- Min

  • 6 -- Max

  • 7 -- Range

  • 8 -- Minority

  • 9 -- Majority (mode)

  • 10 -- Variety

  • 11 -- Variance

  • 12 -- All

Outputs

Label

Name

Type

Description

Vector layer containing the zones

INPUT_VECTOR

[vector: polygon]

The input polygon vector layer with new fields added for the zone statistics.