NEW in 3.8
NEW in 3.6
NEW in 3.6
NEW in 3.6
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.
For lines geometries, the boundaries are the vertices between each features.
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.
Allows features inplace 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.
Allows features inplace modification
Default menu
:
See also
Variable distance buffer (Graphical Modeler only), Multiring 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 (Graphical 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:

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 
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.
Allows features inplace 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):
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. 
Error message  Explanation  Example 

Repeated point  This error happens when a given vertex is repeated.  
Ring selfintersection  This error happens when a geometry touches itself and generates a ring.  
Selfintersection  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 
Error message  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 selfintersection  
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
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.
See also
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.
See also
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.
Allows features inplace 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.
See also
Extent (xmin, xmax, ymin, ymax)
[extent]Extent
NEW in 3.8
¶Creates a new vector layer that contains a single feature with geometry matching a point parameter. It can be used in models to convert a point into a point layer for algorithms which require a layer based input.
See also
Label  Name  Type  Description 

Point  INPUT 
[coordinates]  Input point, including CRS info
(example: If the CRS is not provided, the Project CRS will be used. The point can be specified by clicking on the map canvas. 
Point  OUTPUT 
[vector: point]  Specify the output layer. One of:
The file encoding can also be changed here. 
Label  Name  Type  Description 

Point  OUTPUT 
[vector: point]  The output point vector layer containing the input point. 
Creates wedge shaped buffers from input points.
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.
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.
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.
Allows features inplace 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.
Allows features inplace modification
Default menu
:
See also
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.
Allows features inplace modification
See also
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 to a single feature.
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.
Default menu
:
See also
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, resulting 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.
See also
Input layer
[vector: any]Raster layer
[raster]Band number
[raster band]Value for nodata or nonintersecting 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.
See also
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
:
See also
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.
Allows features inplace modification
See also
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.
Allows features inplace modification
See also
Extended
[vector: line]Extracts M values from geometries into feature attributes.
By default only the M value from the first vertex of each feature is extracted, however the algorithm can optionally calculate statistics on all of the geometry’s M values, including sum, mean, minimum and maximum.
See also
Label  Name  Type  Description 

Input layer  INPUT 
[vector: any]  Input vector layer 
Summaries to calculate  SUMMARIES 
[enumeration] Default: [0] 
Statistics on the M values of a geometry. One or more of:

Output column prefix  COLUMN_PREFIX 
[string] Default: ‘m_’ 
The prefix for the output (M) column 
Extracted  OUTPUT 
[same as input]  Specify the output layer. One of:
The file encoding can also be changed here. 
Label  Name  Type  Description 

Extracted  OUTPUT 
[same as input]  The output vector layer (with M values) 
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.
Default menu
:
Input layer
[vector: any]Vertices
[vector: point]Extracts Z values from geometries into feature attributes.
By default only the Z value from the first vertex of each feature is extracted, however the algorithm can optionally calculate statistics on all of the geometry’s Z values, including sum, mean, minimum and maximum.
See also
Label  Name  Type  Description 

Input layer  INPUT 
[vector: any]  Input vector layer 
Summaries to calculate  SUMMARIES 
[enumeration] Default: [0] 
Statistics on the Z values of a geometry. One or more of:

Output column prefix  COLUMN_PREFIX 
[string] Default: ‘z_’ 
The prefix for the output (Z) column 
Extracted  OUTPUT 
[same as input]  Specify the output layer. One of:
The file encoding can also be changed here. 
Label  Name  Type  Description 

Extracted  OUTPUT 
[same as input]  The output vector layer (with Z values) 
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.
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.
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 multigeometry layer.
Note
M values will be dropped from the output.
Allows features inplace modification
See also
Input layer
[vector: line, polygon]Fixed geometries
[vector: line, polygon]NEW in 3.6
¶This algorithm forces polygon geometries to respect the RightHandRule, in which the area that is bounded by a polygon is to the right of the boundary. In particular, the exterior ring is oriented in a clockwise direction and the interior rings in a counterclockwise direction. The algorithm consumes and produces features with polygon geometries.
Label  Name  Type  Description 

Input features  [vector: polygon]  The input vector 
Label  Name  Type  Description 

Reoriented  [vector: line]  The input features with reoriented polygons 
NEW in 3.6
¶This algorithm splits a line into multiple geodesic segments, whenever the line crosses the antimeridian (±180 degrees longitude).
Splitting at the antimeridian helps the visual display of the lines in some projections. The returned geometry will always be a multipart geometry.
Whenever line segments in the input geometry cross the antimeridian, they will be split into two segments, with the latitude of the breakpoint being determined using a geodesic line connecting the points either side of this segment. The current project ellipsoid setting will be used when calculating this breakpoint.
If the input geometry contains M or Z values, these will be linearly interpolated for the new vertices created at the antimeridian.
Input layer
[vector: line]Split
[vector: line]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.
See also
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.
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.
Allows features inplace modification
See also
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
:
See also
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 nonconnected line parts.
Allows features inplace modification
Input layer
[vector: line]Merged
[vector: lines]Creates geometries which enclose the features from an input layer.
See also
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
Bounding geometry
[vector: polygon]Calculates the minimum enclosing circle which covers each feature in an input layer.
Allows features inplace modification
See also
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 multiring (donuts) buffer for all the features in an input layer, using a fixed or dynamic distance and ring numbers.
Allows features inplace modification
See also
Buffer, Variable distance buffer (Graphical Modeler only), Rectangles, ovals, diamonds (fixed), Rectangles, ovals, diamonds (variable), Single sided buffer
Input layer
[vector: any]Number of rings
[number ]Distance between rings
[number ]Multiring 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.
Allows features inplace modification
Default menu
:
See also
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.
Allows features inplace modification
See also
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.
Allows features inplace modification
See also
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.
Allows features inplace 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 inplace modification
See also
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.
See also
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.
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.
Note
The line layer must have closed shapes in order to be transformed into a polygon.
See also
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.
Default menu
:
See also
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 inplace 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 inplace modification
See also
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.
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.
See also
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 inplace 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.
See also
Input layer
[vector: any]Non null geometries
[vector: any]Null geometries
[vector: any]Inverts the direction of a line layer.
Allows features inplace 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 inplace modification
See also
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). Noncurved geometries will be retained without change.
See also
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. Noncurved geometries will be retained without change.
See also
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.
See also
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.
See also
Input layer
[vector: any]Raster layer
[raster]Band number
[raster band]Value for nodata or nonintersecting 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 “DouglasPeucker” algorithm), area based (“Visvalingam” algorithm) and snapping geometries to grid.
Allows features inplace modification
Default menu
:
See also
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.
See also
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 inplace modification
See also
Input layer
[vector: line, polygon]Iterations
[number ]With many iterations the resulting layer will have many nodes.
Default: 1
Offset
[number ]Larger values will move the resulting layer borders from the input layer ones.
Default: 0.25
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.
See also
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 inplace modification
See also
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]NEW in 3.6
¶This algorithm takes a line (or curve) layer and splits each feature into multiple parts, where each part is of a specified maximum length. Z and M values at the start and end of the new line substrings are linearly interpolated from existing values.
Label  Name  Type  Description 

Input layer  INPUT 
[vector: line]  The input line features 
Length  LENGTH 
[numeric]  The maximum length of a line in the output. 
Split  OUTPUT 
[vector: line]  The sink for the output line features. 
Label  Name  Type  Description 

Split  OUTPUT 
[vector: line]  The new line features  all with line geometries that have a length that is less than or equal to the length specified in the LENGTH paramter. 
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.
Note
Subdividing a geometry can generate geometry parts that may not be valid and may contain selfintersections.
Allows features inplace modification
See also
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 inplace modification
Input layer
[vector: any]Swapped
[vector: any]Creates tapered buffer along line geometries, using a specified start and end buffer diameter.
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.
Allows features inplace 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:
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.
Allows features inplace modification
Input layer
[vector: any]Offset distance (xaxis)
[number ]Displacement to apply on the X axis.
Default: 0.0
Offset distance (yaxis)
[number ]Displacement to apply on the Y axis.
Default: 0.0
Offset distance (zaxis)
[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. This algorithm is only available from the The graphical modeler.
The size of the buffer for a given feature is defined by an attribute, so it allows different features to have different buffer sizes.
See also
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. 
End cap style  END_CAP_STYLE 
[enumeration]  Controls how line endings are handled in the buffer. 
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.
See also
Label  Name  Type  Description 

Input layer  INPUT 
[vector: line]  Input line vector layer 
Segments  SEGMENTS 
[number  dataDefined] Default: 16 
Number of the buffer segments per quarter circle. It can be a unique value (same value for all the features), or it can be taken from features data (the value can depend on feature attributes). 
Buffered  OUTPUT 
[vector: polygon] Default: 
Specify the output (buffer) layer One of:
The file encoding can also be changed here. 
Label  Name  Type  Description 

Buffered  OUTPUT 
[vector: polygon]  Variable buffer polygon layer 
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.
Default menu
:
Label  Name  Type  Description 

Input layer  INPUT 
[vector: point]  Input point vector layer 
Buffer region (% of extent)  BUFFER 
[number] Default: 0.0 
The extent of the output layer will be this much bigger than the extent of the input layer 
Voronoi polygons  OUTPUT 
[vector: polygon] Default: 
Specify the output layer (with the Voronoi polygons). One of:
The file encoding can also be changed here. 
Label  Name  Type  Description 

Voronoi polygons  OUTPUT 
[vector: polygon]  Voronoi polygons of the input point vector layer 