Computes geometric properties of the features in a vector layer and includes them in the output layer.
It generates a new vector layer with the same content as the input one, but with additional attributes, containing geometric measurements based on a selected CRS.
The attributes added to the table depend on the geometry type and dimension of the input layer:
xcoord
), Y (ycoord
), Z (zcoord
) coordinates
and/or M value (mvalue
)length
and, for the LineString and CompoundCurve
geometry types, the feature sinuosity
and straight distance (straightdis
)perimeter
and area
Default menu
:
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Calculate using | CALC_METHOD |
[enumeration] Default: 0 |
Calculation parameters to use for the geometric properties. One of:
|
Added geom info | OUTPUT |
[same as input] Default: |
Specify the output (input copy with geometry) layer One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Added geom info | OUTPUT |
[same as input] | Copy of the input vector layer with the addition of the geometry fields |
Takes a vector or table layer and creates a new layer by aggregating features based
on a group by
expression.
Features for which group by
expression returns the same value are grouped together.
It is possible to group all source features together using constant value in group
by
parameter, example: NULL.
It is also possible to group features by multiple fields using Array function, example: Array(“Field1”, “Field2”).
Geometries (if present) are combined into one multipart geometry for each group. Output attributes are computed depending on each given aggregate definition.
This algorithm allows to use the default aggregates functions of the QGIS Expression engine.
See also
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Group by expression | GROUP_BY |
[tablefield: any] Default: ‘NULL’ |
Choose the grouping field. If NULL all features will be grouped |
Aggregates | AGGREGATES |
[list] | List of output layer field definitions. Example of a field definition: {‘aggregate’: ‘sum’, ‘delimiter’: ‘,’, ‘input’: ‘ $area’, ‘length’: 10, ‘name’: ‘totarea’, ‘precision’: 0, ‘type’: 6} By default, the list contains all the fields of the input layer. In the GUI, you can edit these fields and their definitions, and you can also:
For each of the fields you’d like to retrieve information from, you need to define the following:
|
Load fields from layer | GUI only | [vector: any] | You can load fields from another layer and use them for the aggregation |
Aggregated | OUTPUT |
[same as input] Default: |
Specify the output (aggregate) layer One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Aggregated | OUTPUT |
[same as input] | Multigeometry vector layer with the aggregated values |
Returns the closure of the combinatorial boundary of the input geometries (i.e. the topological boundary of the geometry).
Only for polygon and line layers.
For polygon geometries , the boundary consists of all the lines making up the rings of the polygon.
Boundaries (black dashed line) of the source polygon layer
For lines geometries, the boundaries are the vertices between each features.
Boundary layer (red points) for lines. In yellow a selected feature.
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: line, polygon] | Input line or polygon vector layer |
Boundary | OUTPUT |
[vector: point, line] | Specify the output (boundary) layer. One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Boundary | OUTPUT |
[vector: point, line] | Boundaries from the input layer (point for line, and line for polygon) |
Calculates the bounding box (envelope) of each feature in an input layer. Polygon and line geometries are supported.
Black lines represent the bounding boxes of each polygon feature
Allows features in-place modification
See also
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: line, polygon] | Input line or polygon vector layer |
Bounds | OUTPUT |
[vector: polygon] | Specify the output (bounding box) layer. One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Bounds | OUTPUT |
[vector: polygon] | Bounding boxes of input layer |
Computes a buffer area for all the features in an input layer, using a fixed distance.
It is possible to define also a negative distance for polygon input layers: in this case the buffer will result in a smaller polygon.
In yellow the buffer of point, line and polygon layer
Allows features in-place modification
Default menu
:
See also
Variable distance buffer (Processing Modeler only), Multi-ring buffer (constant distance), Variable width buffer (by M value)
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Distance | DISTANCE |
Default: 10.0 |
Buffer distance (from the boundary of each feature). You can use the Data Defined button on the right to choose a field from which the radius will be calculated. This way you can have different radius for each feature (see Variable distance buffer (Processing Modeler only)). |
Segments | SEGMENTS |
[number] Default: 5 |
Controls the number of line segments to use to approximate a quarter circle when creating rounded offsets. |
End cap style | END_CAP_STYLE |
[enumeration] Default: 0 |
Controls how line endings are handled in the buffer. One of:
![]() Round, flat and square cap styles |
Join style | JOIN_STYLE |
[enumeration] Default: 0 |
Specifies whether round, miter or beveled joins should be used when offsetting corners in a line. Options are:
|
Miter limit | MITER_LIMIT |
[number] Default: 2.0 |
Controls the maximum distance from the offset curve to use when creating a mitered join (only applicable for miter join styles). Minimum: 1. |
Dissolve result | DISSOLVE |
[boolean] Default: False |
Dissolve the final buffer. If ![]() Standard and dissolved buffer |
Buffered | OUTPUT |
[vector: polygon] | Specify the output (buffer) layer. One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Buffered | OUTPUT |
[vector: polygon] | Output (buffer) polygon layer |
Creates a new point layer, with points representing the centroids of the geometries of the input layer.
The centroid can be a single point representing the barycenter (of all parts) of the feature, so it can be outside the feature borders. It can also be a point on each part of the feature.
The attributes associated to each point in the output layer are the same ones associated to the original features.
The red stars represent the centroids of each feature of the input layer.
Allows features in-place modification
Default menu
:
See also
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Create centroid for each part | ALL_PARTS |
Default: False |
If True (checked), a centroid will be created for each part of the geometry |
Centroids | OUTPUT |
[vector: point] | Specify the output (centroid) layer. One of:
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Centroids | OUTPUT |
[vector: point] | Output point vector layer (centroids) |
Performs a validity check on the geometries of a vector layer.
The geometries are classified in three groups (valid, invalid and error) and for each group, a vector layer with its features is generated:
The attribute tables of the generated layers will contain some additional information (“message” for the error layer, “FID” and “_errors” for the invalid layer and only “FID” for the valid layer):
The attribute table of each generated vector layer will contain some additional information (number of errors found and types of error):
Left: the input layer. Right: the valid layer (green), the invalid layer (orange)
Default menu
:
See also
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT_LAYER |
[vector: any] | Input vector layer |
Method | METHOD |
[enumeration] Default: 2 |
Method to use to check validity. Options:
|
Ignore ring self intersection | IGNORE_RING_SELF_INTERSECTION |
[boolean] Default: False |
Ignore self intersecting rings when checking for validity. |
Valid output | VALID_OUTPUT |
[same as input] Default: |
Specify the vector layer to contain a copy of the valid features of the source layer. One of:
The file encoding can also be changed here. |
Invalid output | INVALID_OUTPUT |
[same as input] Default: |
Vector layer containing copy of the invalid features of
the source layer with the field
The file encoding can also be changed here. |
Error output | ERROR_OUTPUT |
[vector: point] Default: |
Point layer of the exact position of the validity
problems detected with the
The file encoding can also be changed here. |
Label | Name | Type | Description |
---|---|---|---|
Count of errors | ERROR_COUNT |
[number] | The number of geometries that caused errors. |
Error output | ERROR_OUTPUT |
[vector: point] | Point layer of the exact position of the validity
problems detected with the message field describing
the error(s) found. |
Count of invalid features | INVALID_COUNT |
[number] | The number of invalid geometries. |
Invalid output | INVALID_OUTPUT |
[same as input] | Vector layer containing copy of the invalid features of
the source layer with the field _errors listing the
summary of the error(s) found. |
Count of valid features | VALID_COUNT |
[number] | The number of valid geometries. |
Valid output | VALID_OUTPUT |
[same as input] | Vector layer containing a copy of the valid features of the source layer. |
Message error | Explanation | Example |
---|---|---|
Repeated point | This error happens when a given vertex is repeated. | ![]() |
Ring self-intersection | This error happens when a geometry touches itself and generates a ring. | ![]() |
Self-intersection | This error happens when a geometry touches itself. | ![]() |
Topology validation error | ||
Hole lies outside shell | ||
Holes are nested | ||
Interior is disconnected | ||
Nested shells | This error happens when a polygon geometry is on top of another polygon geometry. | ![]() |
Duplicate rings | ||
Too few points in geometry component | ||
Invalid coordinate | ||
Ring is not closed |
Message error | Explanation | Example |
---|---|---|
Segment %1 of ring %2 of polygon %3 intersects segment %4 of ring %5 of polygon %6 at %7 | ||
Ring %1 with less than four points | ||
Ring %1 not closed | ||
Line %1 with less than two points | ||
Line %1 contains %n duplicate node(s) at %2 | ||
Segments %1 and %2 of line %3 intersect at %4 | ||
Ring self-intersection | ||
Ring %1 of polygon %2 not in exterior ring | ||
Polygon %1 lies inside polygon %2 | This error happens when a part of MultiPolygon geometry is inside a hole of a MultiPolygon geometry. | ![]() |
Takes a vector layer and collects its geometries into new multipart geometries.
One or more attributes can be specified to collect only geometries belonging to the same class (having the same value for the specified attributes), alternatively all geometries can be collected.
All output geometries will be converted to multi geometries, even those with just a single part. This algorithm does not dissolve overlapping geometries - they will be collected together without modifying the shape of each geometry part.
See the ‘Promote to multipart’ or ‘Aggregate’ algorithms for alternative options.
Default menu
:
See also
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Unique ID fields | FIELD |
[tablefield: any] [list] | Choose one or more attributes to collect the geometries |
Collected | OUTPUT |
[same as input] | Vector layer with collected geometries |
Label | Name | Type | Description |
---|---|---|---|
Collected | OUTPUT |
[same as input] Default: |
Specify the output vector layer for the collected geometries. One of:
The file encoding can also be changed here. |
Computes the concave hull of the features in an input point layer.
See also
Input point layer
[vector: point]Threshold
[number]Number from 0 (maximum concave hull) to 1 (convex hull).
Default: 0.3
Different thresholds used (0.3, 0.6, 0.9)
Allow holes
[boolean]Choose whether to allow holes in the final concave hull.
Default: True
Split multipart geometry into singlepart geometries
[boolean]Check if you want to have singlepart geometries instead of multipart ones.
Default: False
Concave hull
[vector: polygon]This algorithm generates a concave hull polygon from a set of points. If the input layer is a line or polygon layer, it will use the vertices.
The number of neighbors to consider determines the concaveness of the output polygon. A lower number will result in a concave hull that follows the points very closely, while a higher number will have a smoother shape. The minimum number of neighbor points to consider is 3. A value equal to or greater than the number of points will result in a convex hull.
If a field is selected, the algorithm will group the features in the input layer using unique values in that field and generate individual polygons in the output layer for each group.
Input layer
[vector: any]Number of neighboring points to consider
[number]Determines the concaveness of the output polygon. A small number will result in a concave hull that follows the points very closely, while a high number will make the polygon look more like the convex hull (if the number is equal to or larger than the number of features, the result will be the convex hull).
Default (and minimum): 3
Field
[tablefield: any]Optional
If specified, one concave hull polygon is generated for each unique value of the field (by selecting features using this value).
Default: None
Concave hull
[vector: polygon]Generates a new layer based on an existing one, with a different type of geometry.
Not all conversions are possible. For instance, a line layer can be converted to a point layer, but a point layer cannot be converted to a line layer.
Input layer
[vector: any]New geometry type
[enumeration]Geometry type to apply to the output features. Options are:
Note
Conversion types availability depends on the input layer and the conversion chosen: e.g. it is not possible to convert a point to a line.
Converted
[vector: any]Calculates the convex hull for each feature in an input layer.
See the ‘Minimum bounding geometry’ algorithm for a convex hull calculation which covers the whole layer or grouped subsets of features.
Black lines identify the convex hull for each layer feature
Allows features in-place modification
Default menu
:
Input point layer
[vector: any]Convex hull
[vector: polygon]Creates a new vector layer that contains a single feature with geometry matching the extent of the input layer.
It can be used in models to convert a literal extent (xmin
, xmax
, ymin
,
ymax
format) into a layer which can be used for other algorithms which require
a layer based input.
Extent (xmin, xmax, ymin, ymax)
[extent]Extent
Creates wedge shaped buffers from input points.
Wedge buffers
The native output from this algorithm are CurvePolygon geometries, but these may be automatically segmentized to Polygons depending on the output format.
Input layer
[vector: point]Azimuth (degrees from North)
[number Wedge width (in degrees)
[number Width (in degrees) of the buffer. The wedge will extend to half of the angular width either side of the azimuth direction.
Azimuth and width values of the wedge buffer
Outer radius
[number Inner radius
[number Optional
Inner radius value. If 0 the wedge will begin from the source point.
Default: 0.0
Buffers
[vector: polygon]Creates a polygon layer with the delaunay triangulation corresponding to a point layer.
Delaunay triangulation on points
Default menu
:
Input layer
[vector: point]Delaunay triangulation
[vector: polygon]Takes a polygon layer and removes holes in polygons. It creates a new vector layer in which polygons with holes have been replaced by polygons with only their external ring. Attributes are not modified.
An optional minimum area parameter allows removing only holes which are smaller
than a specified area threshold. Leaving this parameter at 0.0
results in all
holes being removed.
Before and after the cleaning
Allows features in-place modification
Cleaned
[vector: polygon]Takes a polygon or line layer and generates a new one in which the geometries have a larger number of vertices than the original one.
If the geometries have Z or M values present then these will be linearly interpolated at the added vertices.
The number of new vertices to add to each segment is specified as an input parameter.
Red points show the vertices before and after the densify
Allows features in-place modification
Default menu
:
Input layer
[vector: line, polygon]Vertices to add
[number]Number of vertices to add to each segment.
Default: 1
Densified
[vector: line, polygon]Takes a polygon or line layer and generates a new one in which the geometries have a larger number of vertices than the original one.
The geometries are densified by adding regularly placed extra vertices inside each segment so that the maximum distance between any two vertices does not exceed the specified distance.
If the geometries have Z or M values present then these will be linearly interpolated at the added vertices.
Example
Specifying a distance 3 would cause the segment [0 0] -> [10 0]
to be converted
to [0 0] -> [2.5 0] -> [5 0] -> [7.5 0] -> [10 0]
, since 3 extra vertices are required
on the segment and spacing these at 2.5 increments allows them to be evenly spaced
over the segment.
Densify geometry at a given interval
Allows features in-place modification
Input layer
[vector: line, polygon]Interval between vertices to add
[number]Maximum distance between two consecutive vertices.
Default: 1.0
Densified
[vector: line, polygon]Takes a vector layer and combines its features into new features. One or more attributes can be specified to dissolve features belonging to the same class (having the same value for the specified attributes), alternatively all features can be dissolved into a single one.
All output geometries will be converted to multi geometries. In case the input is a polygon layer, common boundaries of adjacent polygons being dissolved will get erased.
The resulting attribute table will have the same fields as the input layer. The values in the output layer’s fields are the ones of the first input feature that happens to be processed.
Dissolve the polygon layer on a common attribute
Default menu
:
Input layer
[vector: any]Dissolve field(s)
[tablefield: any] [list]Optional
Features having the same value for the selected field(s) will be replaced with a single one and their geometries are merged.
If no field is provided then all the features are dissolved in a single feature.
Dissolved
[vector: any]Uses values sampled from a band within a raster layer to set the Z value for every overlapping vertex in the feature geometry. The raster values can optionally be scaled by a preset amount.
If Z values already exist in the layer, they will be overwritten with the new value. If no Z values exist, the geometry will be upgraded to include the Z dimension.
Input layer
[vector: any]Raster layer
[raster]Band number
[raster band]Value for nodata or non-intersecting vertices
[number Value to use in case the vertex does not intersect (a valid pixel of) the raster.
Default: 0
Scale
[number Scaling value: the band values are multiplied by this value.
Default: 1.0
Updated
[vector: any]Removes any M (measure) or Z (altitude) values from input geometries.
Input layer
[vector: any]Drop M Values
[boolean]Removes the M values from the geometries.
Default: False
Drop Z Values
[boolean]Removes the Z values from the geometries.
Default: False
Z/M Dropped
[vector: any]Combines selected polygons of the input layer with certain adjacent polygons by erasing their common boundary. The adjacent polygon can be either the one with the largest or smallest area or the one sharing the largest common boundary with the polygon to be eliminated.
Eliminate is normally used to get rid of sliver polygons, i.e. tiny polygons that are a result of polygon intersection processes where boundaries of the inputs are similar but not identical.
Default menu
:
Input layer
[vector: polygon]Merge selection with the neighboring polygon with the
[enumeration]Choose the parameter to use in order to get rid of the selected polygons:
Eliminated
[vector: polygon]Takes a lines layer and creates a new one in which each line layer is replaced by a set of lines representing the segments in the original line.
Each line in the resulting layer contains only a start and an end point, with no intermediate vertices between them.
The original line layer and the exploded one
Allows features in-place modification
Input layer
[vector: line]Exploded
[vector: line]Extends line geometry by a specified amount at the start and end of the line.
Lines are extended using the bearing of the first and last segment in the line.
The red dashes represent the initial and final extension of the original layer
Allows features in-place modification
Extended
[vector: line]Takes a line or polygon layer and generates a point layer with points representing specific vertices in the input lines or polygons.
For instance, this algorithm can be used to extract the first or last vertices in the geometry. The attributes associated to each point are the same ones associated to the line or polygon that the point belongs to.
The vertex indices parameter accepts a comma separated string specifying the indices of the vertices to extract. The first vertex corresponds to an index of 0, the second vertex has an index of 1, etc. Negative indices can be used to find vertices at the end of the geometry, e.g., an index of -1 corresponds to the last vertex, -2 corresponds to the second last vertex, etc.
Additional fields are added to the vertices indicating the specific vertex position (e.g., 0, -1, etc), the original vertex index, the vertex’s part and its index within the part (as well as its ring for polygons), distance along the original geometry and bisector angle of vertex for the original geometry.
Input layer
[vector: line, polygon]Vertex indices
[number]Type the indices of the vertices to extract. The algorithm accepts comma separated
values for many vertices to extract (e.g. -2, 3, 5, 7
).
Default: 0
Vertices
[vector: point]Takes a line or polygon layer and generates a point layer with points representing the vertices in the input lines or polygons.
The attributes associated to each point are the same ones associated to the line or polygon that the point belongs to.
Additional fields are added to the vertices indicating the vertex index (beginning at 0), the feature’s part and its index within the part (as well as its ring for polygons), distance along original geometry and bisector angle of vertex for original geometry.
Vertices extracted for line and polygon layer
Default menu
:
Input layer
[vector: any]Vertices
[vector: point]Filters away vertices based on their M value, returning geometries with only vertex points that have a M value greater than or equal to the specified minimum value and/or less than or equal to the maximum value.
If the minimum value is not specified then only the maximum value is tested, and similarly if the maximum value is not specified then only the minimum value is tested.
The red line represents the black line with only vertices whose M value is <=10.
Note
Depending on the input geometry attributes and the filters used, the resultant geometries created by this algorithm may no longer be valid.
Filtered
[vector: line, polygon]Filters away vertices based on their Z value, returning geometries with only vertex points that have a Z value greater than or equal to the specified minimum value and/or less than or equal to the maximum value.
If the minimum value is not specified then only the maximum value is tested, and similarly if the maximum value is not specified then only the minimum value is tested.
The red line represents the black line with only vertices whose Z value is <=10.
Note
Depending on the input geometry attributes and the filters used, the resultant geometries created by this algorithm may no longer be valid. You may need to run the Fix geometries algorithm to ensure their validity.
Filtered
[vector: line, polygon]Attempts to create a valid representation of a given invalid geometry without losing any of the input vertices. Already valid geometries are returned without further intervention. Always outputs multi-geometry layer.
Note
M values will be dropped from the output.
Allows features in-place modification
Input layer
[vector: line, polygon]Fixed geometries
[vector: line, polygon]Updates existing geometries (or creates new geometries) for input features by use of a QGIS expression.
This allows complex geometry modifications which can utilize all the flexibility of the QGIS expression engine to manipulate and create geometries for output features.
For help with QGIS expression functions, see the inbuilt help for specific functions which is available in the expression builder.
Input layer
[vector: any]Output geometry type
[enumeration]The output geometry strongly depends on the expression you will choose: for instance, if you want to create a buffer then the geometry type has to be a polygon.
Available options are:
Default: 0
Output geometry has z dimension
[boolean]Choose if the output geometry should have the Z dimension.
Default: False
Output geometry has m values
[boolean]Choose if the output geometry should have the M dimension.
Default: False
Geometry expression
[expression]Add the geometry expression you want to use. You can use the button to open the Expression Dialog: the dialog has a list of all the usable expression together with their help and guide.
Default: $geometry
Modified geometry
[vector: any]Creates a point geometry interpolated at a set distance along line or curve geometries.
Z and M values are linearly interpolated from existing values.
If a multipart geometry is encountered, only the first part is considered when calculating the substring.
If the specified distance is greater than the input feature’s length, the resultant feature will have a null geometry.
Interpolated point at 500m of the beginning of the line
Interpolated points
[vector: point]Takes a layer with polygons or multipolygons and returns a new layer in which only the n largest polygons of each multipolygon feature are kept. If a feature has n or fewer parts, the feature will just be copied.
Clockwise from left-up: original multipart feature, one, two and three biggest parts kept
Polygons
[vector: polygon]To keep
[number]Choose how many parts to keep. If 1 is selected, only the biggest part of the feature will be kept.
Default: 1
Biggest parts
[vector: polygon]Returns the portion of a line (or curve) which falls between the specified start and end distances (measured from the beginning of the line).
Z and M values are linearly interpolated from existing values.
If a multipart geometry is encountered, only the first part is considered when calculating the substring.
Substring line with starting distance set at 0 meters and the ending distance at 250 meters.
Allows features in-place modification
Substring
[vector: line]Generates a polygon layer using as polygon rings the lines from an input line layer.
The attribute table of the output layer is the same as the one from of the input line layer.
Default menu
:
Input layer
[vector: line]Polygons
[vector: polygon]Joins all connected parts of MultiLineString geometries into single LineString geometries.
If any parts of the input MultiLineString geometries are not connected, the resultant geometry will be a MultiLineString containing any lines which could be merged and any non-connected line parts.
Allows features in-place modification
Input layer
[vector: line]Merged
[vector: lines]Creates geometries which enclose the features from an input layer.
Input layer
[vector: any]Field
[tablefield: any]Optional
Features can be grouped by a field. If set, this causes the output layer to contain one feature per grouped value with a minimal geometry covering only the features with matching values.
Geometry type
[enumeration]Numerous enclosing geometry types are supported:
Default: 0
Clockwise from left-up: envelopes, oriented rectangle, circle, convex hull
Bounding geometry
[vector: polygon]Calculates the minimum enclosing circle which covers each feature in an input layer.
Enclosing circles for each feature
Allows features in-place modification
Input layer
[vector: any]Number of segment in circles
[number]Choose the number of segment for each circle.
Default: 72
Minimum enclosing circles
[vector: polygon]Computes multi-ring (donuts) buffer for all the features in an input layer, using a fixed or dynamic distance and ring numbers.
Multi-ring buffer for line, point and polygon layer
Allows features in-place modification
Input layer
[vector: any]Number of rings
[number Distance between rings
[number Multi-ring buffer (constant distance)
Splits the multipart input layers into single features.
The attributes of the output layers are the same of the original ones but divided into single features.
Left the multipart source layer and right the single part output result
Allows features in-place modification
Default menu
:
Input layer
[vector: any]Single parts
[vector: any]Offsets lines by a specified distance. Positive distances will offset lines to the left, and negative distances will offset them to the right.
In blue the source layer, in red the offset one
Allows features in-place modification
Input layer
[vector: line]Distance
[number Distance of the offset.
Default: 10.0
Segment
[number]Number of line segments to use to approximate a quarter circle when creating rounded offsets.
Default: 8
Join style
[enumeration]Specify whether round, miter or beveled joins should be used when offsetting corners in a line. Options are:
Default: 0
Miter limit
[number]Only applicable for mitered join styles, and controls the maximum distance from the offset curve to use when creating a mitered join.
Default: 2.0
Offset
[vector: line]Calculates the minimum area rotated rectangle which covers each feature in an input layer.
Oriented minimum bounding box
Allows features in-place modification
Input layer
[vector: any]Bounding boxes
[vector: polygon]Takes a line or polygon layer and attempts to orthogonalize all the geometries in the layer. This process shifts the vertices in the geometries to try to make every angle in the geometry either a right angle or a straight line.
In blue the source layer while the red line is the orthogonalized result
Allows features in-place modification
Input layer
[vector: line, polygon]Maximum angle tolerance (degrees)
[number]Maximum algorithm iterations
[number]Orthogonalized
[vector: line, polygon]Returns a point guaranteed to lie on the surface of a geometry.
Allows features in-place modification
Point
[vector: point]Creates points at regular intervals along line or polygon geometries. Created points will have new attributes added for the distance along the geometry and the angle of the line at the point.
An optional start and end offset can be specified, which controls how far from the start and end of the geometry the points should be created.
Points created along the source line layer
Input layer
[vector: line, polygon]Distance
[number]Distance between two consecutive points along a geometry.
Default: 100
Start offset
[number]Distance from the beginning of the input line, representing the position of the first point.
Default: 0
End offset
[number]Distance from the end of the input line, representing the position beyond which no point feature shoud be created.
Default: 0
Points
[vector: point]Given a distance of proximity, identifies nearby point features and radially distributes them over a circle whose center represents their barycenter. A convenient tool to scatter overlaid features.
Input layer
[vector: point]Minimum distance to other points
[number]Distance below which point features are considered close. Close features are distributed altogether.
Default: 1.0
Displacement distance
[number]Radius of the circle on which close features are placed.
Default: 1.0
Horizontal distribution for two point case
[boolean]When only two points are identified as close, aligns them horizontally on the circle instead of vertically.
Default: False
Displaced
[vector: point]Calculates the pole of inaccessibility for a polygon layer, which is the most distant internal point from the boundary of the surface.
This algorithm uses the ‘polylabel’ algorithm (Vladimir Agafonkin, 2016), which is an iterative approach guaranteed to find the true pole of inaccessibility within a specified tolerance. A more precise tolerance (lower value) requires more iterations and will take longer to calculate.
The distance from the calculated pole to the polygon boundary will be stored as a new attribute in the output layer.
Pole of inaccessibility
Input layer
[vector: polygon]Tolerance
[number]Set the tolerance for the calculation.
Default: 1.0
Point
[vector: point]Creates a polygon layer whose features boundaries are generated from a closed line layer features.
The yellow polygons generated from the closed lines
Note
The line layer must have closed shapes in order to be transformed into a polygon.
Input layer
[vector: line]Keep table structure of line layer
[boolean]Optional
Check to copy the original attribute of the line layer.
Default: False
Polygons from lines
[vector: polygon]Takes a polygon layer and creates a line layer, with lines representing the boundaries of the polygons in the input layer.
Black lines as the result of the algorithm
Default menu
:
Input layer
[vector: polygon]Lines
[vector: line]Projects point geometries by a specified distance and bearing (azimuth), creating a new point layer with the projected points.
Allows features in-place modification
Projected
[vector: point]Takes a vector layer with singlepart geometries and generates a new one in which all geometries are multipart.
Input features which are already multipart features will remain unchanged.
This algorithm can be used to force geometries to multipart types in order to be compatible with data providers that require multipart features.
Allows features in-place modification
Input layer
[vector: any]Multiparts
[vector: any]Creates a buffer area for all the features in an input layer with different shape choice.
Parameters can vary depending on the shape chosen.
Different buffer shapes
Input layer
[vector: point]Buffer shape
[enumeration]Different shapes available:
Default: 0
Width
[number]Width of the buffer shape.
Default: 1.0
Height
[number]Height of the buffer shape.
Default: 1.0
Rotation
[number]Optional
Rotation of the buffer shape.
Default: 0.0
Number of segment
[number]How many segment should have the buffer shape.
Default: 36
Output
[vector: polygon]Creates a buffer area for all the features in an input layer with different shape choice.
Buffer shape parameters are specified through attribute of the input layer.
Different buffer shapes with different parameters
Input layer
[vector: point]Buffer shape
[enumeration]Different shape available:
Default: 0
Width
[tablefield: numeric]Width of the buffer shape.
Default: 1.0
Height
[tablefield: numeric]Height of the buffer shape.
Default: 1.0
Rotation
[tablefield: numeric]Optional
Rotation of the buffer shape.
Default: 0.0
Number of segment
[number]How many segment should have the buffer shape.
Default: 36
Output
[vector: polygon]Removes duplicate vertices from features, wherever removing the vertices does not result in a degenerate geometry.
The tolerance parameter specifies the tolerance for coordinates when determining whether vertices are identical.
By default, Z values are not considered when detecting duplicate vertices. E.g. two vertices with the same X and Y coordinate but different Z values will still be considered duplicate and one will be removed. If the Use Z Value parameter is true, then the Z values are also tested and vertices with the same X and Y but different Z will be maintained.
Note
Duplicate vertices are not tested between different parts of a multipart geometry, e.g. a multipoint geometry with overlapping points will not be changed by this method.
Allows features in-place modification
Input layer
[vector: any]Tolerance
[number Vertices closer than the specified distance are considered duplicates.
Default:0.000001
Use Z value
[boolean Allows to consider the Z coordinate when detecting duplicate vertices ie two points at the same X,Y coordinate but with different Z value are not set as duplicates.
Default: False
Cleaned
[vector: any]Removes any features which do not have a geometry from a vector layer.
All other features will be copied unchanged.
The features with null geometries can be saved to a separate layer.
Input layer
[vector: any]Non null geometries
[vector: any]Null geometries
[vector: any]Inverts the direction of a line layer.
Before and after the direction inversion
Allows features in-place modification
Input layer
[vector: line]Reversed
[vector: line]Rotates feature geometries by the specified angle clockwise. The rotation occurs around each feature’s centroid, or optionally around a unique preset point.
Allows features in-place modification
Input layer
[vector: any]Rotation (degrees clockwise)
[number Angle of the rotation in degrees.
Default: 0.0
Rotation anchor point (x, y)
[point]Optional
X,Y coordinates of the point to rotate the features around. If not set the rotation occurs around each feature’s centroid.
Rotated
[vector: any]Segmentizes a geometry by converting curved sections to linear sections.
The segmentization is performed by specifying the maximum allowed radius angle between vertices on the straightened geometry (e.g the angle of the arc created from the original arc center to consecutive output vertices on the linearized geometry). Non-curved geometries will be retained without change.
Segmentized
[vector: line, polygon]Segmentizes a geometry by converting curved sections to linear sections.
The segmentization is performed by specifying the maximum allowed offset distance between the original curve and the segmentized representation. Non-curved geometries will be retained without change.
Segmentized
[vector: line, polygon]Sets the M value for geometries in a layer.
If M values already exist in the layer, they will be overwritten with the new value. If no M values exist, the geometry will be upgraded to include M values and the specified value used as the initial M value for all geometries.
Tip
Use the Identify Features button to check the added M value:
the results are available in the Identify Results dialog.
M Added
[vector: any]Uses values sampled from a band within a raster layer to set the M value for every overlapping vertex in the feature geometry. The raster values can optionally be scaled by a preset amount.
If M values already exist in the layer, they will be overwritten with the new value. If no M values exist, the geometry will be upgraded to include M values.
Input layer
[vector: any]Raster layer
[raster]Band number
[raster band]Value for nodata or non-intersecting vertices
[number Value to use in case the vertex does not intersect (a valid pixel of) the raster.
Default: 0.0
Scale factor
[number Scaling value: the band values are multiplied by this value.
Default: 1.0
Updated
[vector: any]Sets the Z value for geometries in a layer.
If Z values already exist in the layer, they will be overwritten with the new value. If no Z values exist, the geometry will be upgraded to include Z values and the specified value used as the initial Z value for all geometries.
Tip
Use the Identify Features button to check the added Z value:
the results are available in the Identify Results dialog.
Z Added
[vector: any]Simplifies the geometries in a line or polygon layer. It creates a new layer with the same features as the ones in the input layer, but with geometries containing a lower number of vertices.
The algorithm gives a choice of simplification methods, including distance based (the “Douglas-Peucker” algorithm), area based (“Visvalingam” algorithm) and snapping geometries to grid.
Clockwise from top left: source layer and increasing simplification tolerances
Allows features in-place modification
Default menu
:
Input layer
[vector: line, polygon]Simplification method
[enumeration]Method of the simplification.
Options:
Default: 0
Tolerance
[number Threshold tolerance (in units of the layer): if the distance between two nodes is smaller than the tolerance value, the segment will be simplified and vertices will be removed.
Default: 1.0
Simplified
[vector: line, polygon]Computes a buffer on lines by a specified distance on one side of the line only.
Buffer always results in a polygon layer.
Left versus right side buffer on the same vector line layer
Input layer
[vector: line]Distance
[number]Distance radius of the buffer.
Default: 10.0
Side
[enumeration]Choose which side the buffer should be created:
Default: 0
Segments
[number]Controls the number of line segments to use to approximate a quarter circle when creating rounded offsets.
Default: 8
Join style
[enumeration]Specifies whether round, miter or beveled joins should be used when offsetting corners in a line. Options are:
Default: 0
Miter limit
[number]Only applicable for mitered join styles, and controls the maximum distance from the offset curve to use when creating a mitered join.
Default: 2.0
Buffer
[vector: polygon]Smooths the geometries in a line or polygon layer. It creates a new layer with the same features as the ones in the input layer, but with geometries containing a higher number of vertices and corners in the geometries smoothed out.
The iterations parameter dictates how many smoothing iterations will be applied to each geometry. A higher number of iterations results in smoother geometries with the cost of greater number of nodes in the geometries.
The offset parameter controls how “tightly” the smoothed geometries follow the original geometries. Smaller values results in a tighter fit, and larger values will create a looser fit.
The maximum angle parameter can be used to prevent smoothing of nodes with large angles. Any node where the angle of the segments to either side is larger than this will not be smoothed. For example, setting the maximum angle to 90 degrees or lower would preserve right angles in the geometry.
Allows features in-place modification
Input layer
[vector: line, polygon]Iterations
[number With many iterations the resulting layer will have many nodes.
Default: 1
Different number of iterations cause smoother geometries
Offset
[number Larger values will move the resulting layer borders from the input layer ones.
Default: 0.25
In blue the input layer. Offset value of 0.25 results in the red line while offset value of 0.50 results in the green line
Maximum node angle to smooth
[number Every node below this value will be smoothed.
Default: 180.0
Smoothed
[vector: line, polygon]Snaps the geometries in a layer either to the geometries from another layer, or to geometries within the same layer.
Matching is done based on a tolerance distance, and vertices will be inserted or removed as required to make the geometries match the reference geometries.
Input layer
[vector: any]Reference layer
[vector: any]Tolerance
[number]Control how close input vertices need to be to the reference layer geometries before they are snapped. This distance is specified in layer units.
Default: 10.0
Behavior
[enumeration]Snapping can be done on an existing node or a segment (its closest point to the vertex to move). Choose between different snapping options:
Default: Prefer aligning nodes, insert extra vertices where required
Snapped geometry
[vector: any]Modifies the coordinates of geometries in a vector layer, so that all points or vertices are snapped to the closest point of a grid.
If the snapped geometry cannot be calculated (or is totally collapsed) the feature’s geometry will be cleared.
Snapping can be performed on the X, Y, Z or M axis. A grid spacing of 0 for any axis will disable snapping for that axis.
Note
Snapping to grid may generate an invalid geometry in some corner cases.
Allows features in-place modification
Input layer
[vector: any]X Grid Spacing
[number Spacing of the grid on the X axis.
Default: 1.0
Y Grid Spacing
[number Spacing of the grid on the Y axis.
Default: 1.0
Z Grid Spacing
[number Spacing of the grid on the Z axis.
Default: 0.0
M Grid Spacing
[number Spacing of the grid on the M axis.
Default: 0.0
Snapped
[vector: any]Subdivides the geometry. The returned geometry will be a collection containing subdivided parts from the original geometry, where no part has more than the specified maximum number of nodes.
This is useful for dividing a complex geometry into less complex parts, easier to spatially index and faster to perform spatial operations. Curved geometries will be segmentized before subdivision.
Left the input layer, middle maximum nodes value is 100 and right maximum value is 200
Note
Subdividing a geometry can generate geometry parts that may not be valid and may contain self-intersections.
Allows features in-place modification
Subdivided
[vector: any]Switches the X and Y coordinate values in input geometries.
It can be used to repair geometries which have accidentally had their latitude and longitude values reversed.
Allows features in-place modification
Input layer
[vector: any]Swapped
[vector: any]Creates tapered buffer along line geometries, using a specified start and end buffer diameter.
Tapered buffer example
Input layer
[vector: line]Start width
[number Represents the radius of the buffer applied at the start point of the line feature.
Default: 0.0
End width
[number Represents the radius of the buffer applied at the end point of the line feature.
Default: 1.0
Segments
[number Number of the buffer segments.
Default: 16
Buffered
[vector: polygon]Tessellates a polygon geometry layer, dividing the geometries into triangular components.
The output layer consists of multipolygon geometries for each input feature, with each multipolygon consisting of multiple triangle component polygons.
Tessellated polygon (right)
Allows features in-place modification
Input layer
[vector: polygon]Tesselated
[vector: polygon]Creates transects on vertices for (multi)linestring.
A transect is a line oriented from an angle (by default perpendicular) to the input polylines (at vertices).
Field(s) from feature(s) are returned in the transect with these new fields:
Dashed red lines represent the transect of the input line layer
Input layer
[vector: line]Length of the transect
[number Length in map unit of the transect.
Default: 5.0
Angle in degrees from the original line at the vertices
[number Change the angle of the transect.
Default: 90.0
Side to create the transect
[enumeration]Choose the side of the transect. Available options are:
Default: 0
Transect
[vector: line]Moves the geometries within a layer, by offsetting with a predefined X and Y displacement.
Z and M values present in the geometry can also be translated.
Dashed lines represent the translated geometry of the input layer
Allows features in-place modification
Input layer
[vector: any]Offset distance (x-axis)
[number Displacement to apply on the X axis.
Default: 0.0
Offset distance (y-axis)
[number Displacement to apply on the Y axis.
Default: 0.0
Offset distance (z-axis)
[number Displacement to apply on the Z axis.
Default: 0.0
Offset distance (m values)
[number Offset value to apply on M.
Default: 0.0
Translated
[vector: any]Computes a buffer area for all the features in an input layer.
The size of the buffer for a given feature is defined by an attribute, so it allows different features to have different buffer sizes.
Label | Name | Type | Description |
---|---|---|---|
Input layer | INPUT |
[vector: any] | Input vector layer |
Distance field | DISTANCE |
[tablefield: numeric] | Attribute for the distance radius of the buffer |
Segments | SEGMENTS |
[number] Default: 5 |
Controls the number of line segments to use to approximate a quarter circle when creating rounded offsets. |
Dissolve result | DISSOLVE |
[boolean] Default: False |
Choose to dissolve the final buffer, resulting in a single feature covering all input features. ![]() Normal and dissolved buffer |
End cap style | END_CAP_STYLE |
[enumeration] | Controls how line endings are handled in the buffer. ![]() Round, flat and square cap styles |
Join style | JOIN_STYLE |
[enumeration] | Specifies whether round, miter or beveled joins should be used when offsetting corners in a line. |
Miter limit | MITER_LIMIT |
[number] Default: 2.0 |
Only applicable for mitered join styles, and controls the maximum distance from the offset curve to use when creating a mitered join. |
Label | Name | Type | Description |
---|---|---|---|
Buffer | OUTPUT |
[vector: polygon] | Buffer polygon vector layer. |
Creates variable width buffers along lines, using the M value of the line geometries as the diameter of the buffer at each vertex.
Variable buffer example
Buffered
[vector: polygon]Takes a points layer and generates a polygon layer containing the Voronoi polygons (known also as Thiessen polygons) corresponding to those input points.
Any location within a Voronoi polygon is closer to the associated point than to any other point.
Voronoi polygons
Default menu
:
Input layer
[vector: point]Buffer region
[number]Area of the Voronoi polygons or of the input layer.
Default: 0.0
Voronoi polygons
[vector: polygon]