Vector overlay

Clip

Clips a vector layer using the features of an additional polygon layer.

Only the parts of the features in the input layer that fall within the polygons of the overlay layer will be added to the resulting layer.

Warning

Feature modification

The attributes of the features are not modified, although properties such as area or length of the features will be modified by the clipping operation. If such properties are stored as attributes, those attributes will have to be manually updated.

This algorithm uses spatial indexes on the providers, prepared geometries and apply a clipping operation if the geometry isn’t wholly contained by the mask geometry.

../../../../_images/clip4.png

Clipping operation between a two-features input layer and a single feature overlay layer (left) - resulting features are moved for clarity (right)

checkbox Allows features in-place modification

Default menu: Vector ‣ Geoprocessing Tools

Parameters

Input layer [vector: any]
Layer containing the features to be clipped.
Overlay layer [vector: polygon]
Layer containing the clipping features.

Outputs

Clipped [vector: any]
Layer containing features from the input layer split by the overlay layer.

See also

Intersection

Difference

Extracts features from the input layer that don’t fall within the boundaries of the overlay layer.

Input layer features that partially overlap the overlay layer feature(s) are split along the boundary of those feature(s) and only the portions outside the overlay layer features are retained.

Attributes are not modified (see warning).

../../../../_images/difference1.png

Difference operation between a two-features input layer and a single feature overlay layer (left) - resulting features are moved for clarity (right)

checkbox Allows features in-place modification

Default menu: Vector ‣ Geoprocessing Tools

Parameters

Input layer [vector: any]
Layer to extract (parts of) features from.
Overlay layer [vector: any]
Layer containing the overlapping features to compare to, acting as a subtracting layer.

Outputs

Difference [vector: any]
Layer containing (parts of) features from the input layer not overlapping the overlay layer.

Extract/clip by extent

Creates a new vector layer that only contains features which fall within a specified extent.

Any features which intersect the extent will be included.

Parameters

Input layer [vector: any]
Layer to extract (parts of) features from.
Extent (xmin, xmax, ymin, ymax) [extent]
Extent of the clipping.
Clip features to the extent [boolean]
If checked, output geometries will be automatically converted to multi geometries to ensure uniform output types. Moreover the geometries will be clipped to the extent chosen instead of taking the whole geometry as output.

Outputs

Extracted [vector: any]
Layer containing the clipped features.

Intersection

Extracts the portions of features from the input layer that overlap features in the overlay layer.

Features in the intersection layer are assigned the attributes of the overlapping features from both the input and overlay layers.

Attributes are not modified (see warning).

../../../../_images/intersection.png

Intersection operation between a two-features input layer and a single feature overlay layer (left) - resulting features are moved for clarity (right)

Default menu: Vector ‣ Geoprocessing Tools

Parameters

Input layer [vector: any]
Layer to extract (parts of) features from.
Overlay layer [vector: any]
Layer containing the overlapping features to compare to.
Input fields to keep [tablefield: any] [list]

Optional

Field(s) of the input layer to keep in the output. If no fields are chosen all fields are taken.

Overlay fields to keep [tablefield: any] [list]

Optional

Field(s) of the overlay layer to keep in the output. If no fields are chosen all fields are taken.

Outputs

Intersection [vector: any]
Layer containing (parts of) features from the input layer overlapping the overlay layer.

See also

Clip

Line intersections

Creates point features where the lines from both layers intersect.

../../../../_images/line_intersection.png

Points of intersection

Default menu: Vector ‣ Analysis Tools

Parameters

Input layer [vector: line]
Input layer.
Intersect layer [vector: line]
Layer to use in the intersection operation.
Input fields to keep [tablefield: any] [list]

Optional

Field(s) of the input layer to keep in the output. If no fields are chosen all fields are taken.

Intersect fields to keep [tablefield: any] [list]

Optional

Field(s) of the intersect layer to keep in the output. If no fields are chosen all fields are taken.

Outputs

Intersections [vector: point]
Point vector layer of the intersection.

Split with lines

Splits the lines or polygons in one layer using the lines in another layer to define the breaking points. Intersection between geometries in both layers are considered as split points.

Output will contain multi geometries for split features.

../../../../_images/split_with_lines.png

Split lines

checkbox Allows features in-place modification

Parameters

Input layer [vector: line, polygon]
Layer containing the lines or polygons to split.
Split layer [vector: line]
Line layer whose lines are used to define the breaking points.

Outputs

Split [vector: line, polygon]
Output layer with split lines or polygons from input layer.

Symmetrical difference

Creates a layer containing features from both the input and overlay layers but with the overlapping areas between the two layers removed.

The attribute table of the symmetrical difference layer contains attributes and fields from both the input and overlay layers.

Attributes are not modified (see warning).

../../../../_images/symmetrical_difference.png

Symmetrical difference operation between a two-features input layer and a single feature overlay layer (left) - resulting features are moved for clarity (right)

Default menu: Vector ‣ Geoprocessing Tools

Parameters

Input layer [vector: any]
First layer to extract (parts of) features from.
Overlay layer [vector: any]
Second layer to extract (parts of) features from.

Outputs

Symmetrical difference [vector: any]
Layer containing (parts of) features from each layer not overlapping the other layer.

See also

Difference

Union

Checks overlaps between features within the input layer and creates separate features for overlapping and non-overlapping parts. The area of overlap will create as many identical overlapping features as there are features that participate in that overlap.

../../../../_images/union1.png

Union operation with a single input layer of three overlapping features (left) - resulting features are moved for clarity (right)

An overlay layer can also be used, in which case features from each layer are split at their overlap with features from the other one, creating a layer containing all the portions from both input and overlay layers. The attribute table of the union layer is filled with attribute values from the respective original layer for non-overlapping features, and attribute values from both layers for overlapping features.

../../../../_images/union_with_overlay.png

Union operation between a two-features input layer and a single feature overlay layer (left) - resulting features are moved for clarity (right)

Note

For union(A,B) algorithm, if there are overlaps among geometries of layer A or among geometries of layer B, these are not resolved: you need to do union(union(A,B)) to resolve all overlaps, i.e. run single layer union(X) on the produced result X=union(A,B).

Default menu: Vector ‣ Geoprocessing Tools

Parameters

Input layer [vector: any]
Input vector layer to split at any intersections.
Overlay layer [vector: any]

Optional

Layer that will be combined to the first one.

Outputs

Union [vector: any]
Layer containing all the overlapping and non-overlapping parts from the processed layer(s).