24.1.3. Check Geometry

24.1.3.1. Dangle-end lines

Detects dangle-end lines in line geometries and reports them as errors. A dangle-end line is a line feature that terminates at a vertex connected to only one segment, resulting in an endpoint without a proper connection.

Fig. 24.2 Identifying dangle-end features (in red) and vertices (yellow).

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Dangle-end errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Dangle-end features Optional	OUTPUT	[vector: line] Default: [Skip output]	Line layer containing the identified dangle-end line features. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Dangle-end errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part containing the dangle-end. gc_ringidx: the index of the feature’s geometry ring containing the dangle-end. gc_vertidx: the vertex index of the dangle-end in the feature’s geometry ring. gc_errorx: the x coordinate of the dangle-end. gc_errory: the y coordinate of the dangle-end. gc_error UNIQUE_ID field: the unique ID of the input feature with the dangle-end.
Dangle-end features	OUTPUT	[vector: line]	Output line layer containing the input dangle-end features. If no dangle-end features are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrydangle

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.2. Degenerate polygons

Checks the polygons with less than 3 points, which are degenerate polygons. Degenerate polygons are errors.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Degenerate polygons errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the centroid of the degenerate polygons. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Degenerate polygons features Optional	OUTPUT	[vector: polygon] Default: [Skip output]	Specification of the output layer containing the degenerate polygons. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Degenerate polygons errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the geometry part of the degenerate polygon. gc_ringidx: the index of the ring of the degenerate polygon. gc_vertidx gc_errorx: the x coordinate of the centroid of the degenerate polygon gc_errory: the y coordinate of the centroid of the degenerate polygon gc_error UNIQUE_ID field: the unique ID of the input feature that is degenerate.
Degenerate polygons features	OUTPUT	[vector: polygon]	Output polygon layer with features containing the degenerate polygons. If no degenerate polygon features are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrydegeneratepolygon

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.3. Duplicated geometries

Checks for duplicated geometries in a vector layer, and reports them as errors.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: geometry]	Layer with the geometries to check
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification
Duplicate geometries errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Duplicate geometries Optional	OUTPUT	[vector: same as input] Default: [Skip output]	Specification of the output layer containing the geometries that were found to be duplicated. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Duplicate geometries errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of the centroid of the duplicate geometry. gc_errory: the y coordinate of the centroid of the duplicate geometry. gc_error: the indices of the duplicate geometry (all except the highest index). UNIQUE_ID field: the unique ID of the input feature that is a duplicate.
Duplicate geometries	OUTPUT	[vector: same as input]	Output layer containing the geometries that were found to be duplicated. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryduplicate

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.4. Duplicated vertices

Checks for duplicated vertices in line or polygon geometries, and reports them as errors.

See also

Delete duplicated vertices, Remove duplicate vertices

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line, polygon]	Layer with the geometries to check
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification
Duplicated vertices errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Duplicated vertices features Optional	OUTPUT	[vector: same as input] Default: [Skip output]	Specification of the output layer containing the features with duplicated vertices. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Duplicated vertices errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part containing the duplicate vertex. gc_ringidx: the index of the feature’s geometry ring containing the duplicate vertex. gc_vertidx: the index of the duplicate vertex in the feature’s geometry ring. gc_errorx: the x coordinate of the duplicate vertex. gc_errory: the y coordinate of the duplicate vertex. gc_error UNIQUE_ID field: the unique ID of the input feature that has duplicate vertices.
Duplicated vertices features	OUTPUT	[vector: same as input]	Output layer containing the features with duplicated vertices. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryduplicatenodes

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.5. Features inside polygon

Checks the input geometries contained in the polygons from the polygon layers list. A polygon layer can be checked against itself. Any contained features are reported as errors.

Fig. 24.3 Reporting errors on features inside a polygon.

See also

Delete features

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: geometry]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Polygon layers	POLYGONS	[vector: polygon][list]	List of polygon layers to check against.
Errors from contained features	ERRORS	[vector: point] Default: [Create temporary layer]	Point layer representing the contained features. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Contained features Optional	OUTPUT	[vector: same as input] Default: [Skip output]	Specification of the output layer containing features within the checked polygons. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Errors from contained features	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of the centroid of the contained feature. gc_errory: the y coordinate of the centroid of the contained feature. gc_error: the layer name and feature ID of a polygon that contains the feature. UNIQUE_ID field: the unique ID of the input feature that is contained within another.
Contained features	OUTPUT	[vector: same as input]	Output layer containing features within the checked polygons. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrycontained

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.6. Holes

Detects holes in polygon geometries and reports them as errors.

Fig. 24.4 Reporting errors for holes on a polygon feature.

See also

Fill holes

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: polygon]	Layer with the geometries to check
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification
Holes errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Polygons with holes Optional	OUTPUT	[vector: polygon] Default: [Skip output]	Polygon layer with the features containing holes. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Holes errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part containing the hole. gc_ringidx: the index of the feature’s geometry ring containing the hole. gc_vertidx gc_errorx: the x coordinate of the centroid of the hole. gc_errory: the y coordinate of the centroid of the hole. gc_error UNIQUE_ID field: the unique ID of the input feature that has a hole.
Polygon with holes	OUTPUT	[vector: polygon]	Output polygon layer with features containing holes. If no holes are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryhole

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.7. Lines intersecting each other

Checks intersections between line geometries within a layer. Intersections between two different lines are errors.

See also

Line intersections, Intersection, Self-intersections

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Intersection errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the intersections location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Intersecting feature Optional	OUTPUT	[vector: line] Default: [Skip output]	Specification of the output layer for features intersecting each other. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Intersection errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part where the intersection occurs. gc_ringidx gc_vertidx gc_errorx: the x coordinate of the intersection point. gc_errory: the y coordinate of the intersection point. UNIQUE_ID field: the unique ID of an intersecting input feature. gc_error: the layer name and index of the other intersecting feature.
Intersecting feature	OUTPUT	[vector: line]	Output layer containing, for each identified intersection, the feature (with same UNIQUE_ID value) it belongs to. If no intersections are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrylineintersection

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.8. Lines intersecting other layer

Checks if the input line layer features intersect with the check layer features. An input feature that intersects with a check layer feature is an error.

See also

Line intersections, Intersection, Self-intersections

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Check layer	CHECK_LAYER	[vector: line, polygon]	Layer with the geometries to check against.
Line intersecting other layer errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output point layer containing the locations of intersection errors. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Line intersecting other layer features Optional	OUTPUT	[line] Default: [Skip output]	Line layer with the input features that intersect features in the check layer. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Line intersecting other layer errors	ERRORS	[vector: point]	Output point layer representing the error location and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part where the intersection occurs. gc_ringidx gc_vertidx gc_errorx: the x coordinate of the intersection point. gc_errory: the y coordinate of the intersection point. UNIQUE_ID field: the unique ID of the intersecting input feature. gc_error: the index of the check layer where the intersection occurs.
Line intersecting other layer features	OUTPUT	[vector: line]	Output layer containing, for each identified intersection, the input feature it belongs to. If no intersections are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrylinelayerintersection

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.9. Missing vertices along borders

Checks for missing vertices along polygon borders. To be topologically correct, a vertex at the junction of two polygons must be present on both polygons. Missing vertices are errors.

Fig. 24.5 Reporting errors for missing vertices on polygon features.

See also

Add missing vertices along borders

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Missing vertices errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Missing vertices features Optional	OUTPUT	[vector: polygon] Default: [Skip output]	Polygon layer with the features whose vertices are missing. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Missing vertices errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of the missing vertex. gc_errory: the y coordinate of the missing vertex. gc_error UNIQUE_ID field: the unique ID of the input feature that has a missing vertex.
Missing vertices features	OUTPUT	[vector: polygon]	Output polygon layer with features whose vertices are missing. There will be as many (duplicate) features as there are missing vertices in each geometry. If no vertices are missing, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrymissingvertex

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.10. Overlaps

Calculates overlapping areas in polygon geometries, and reports areas smaller than a given minimum as errors.

Fig. 24.6 Hashed polygons indicate overlapping areas smaller than the specified minimum.

See also

Delete overlaps, Validate coverage

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Minimum overlap area	MIN_OVERLAP_AREA	[numeric: double]	Minimum area of the overlap to be reported as an error. If set to 0, all overlaps are reported.
Overlap errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing centroid points of the overlapping areas. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Overlap features Optional	OUTPUT	[vector: polygon] Default: [Skip output]	Specification of the output layer for features containing overlaps. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Overlap errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_errorx: the x coordinate of the centroid of the overlapping area. gc_errory: the y coordinate of the centroid of the overlapping area. gc_error: the area of the overlapping geometry. UNIQUE_ID field: the unique ID of an overlapped input feature. gc_overlap_feature_{unique_id}: the UNIQUE_ID field value for the other overlapping feature.
Overlap features	OUTPUT	[vector: polygon]	Output layer containing the overlapping areas. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryoverlap

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.11. Points outside lines

Checks if the points in the input layer are covered by a line in the selected line layers. A point not covered by a line is an error.

Fig. 24.7 Reporting errors on points not covered by a line.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: point]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Line layers	LINES	[vector: line][list]	Layer(s) with the lines to check against.
Points not covered by a line	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing points not covered by a line. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Points not covered by a line	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of point outside the lines. gc_errory: the y coordinate of point outside the lines. gc_error UNIQUE_ID field: the unique ID of the input feature that is outside the lines.

Python code

Algorithm ID: native:checkgeometrypointcoveredbyline

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.12. Points outside polygons

Checks if points from the input layer are in polygons from the selected polygon layers. Points that are not fully inside polygons are errors.

Fig. 24.8 Reporting errors on points outside polygons.

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: point]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Polygon layers	POLYGONS	[vector: polygon][list]	Layer(s) with the polygons to check against.
Points outside polygons errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing points outside the polygons. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Points outside polygons errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of point outside the polygons. gc_errory: the y coordinate of point outside the polygons. gc_error UNIQUE_ID field: the unique ID of the input feature that is outside the polygons.

Python code

Algorithm ID: native:checkgeometrypointinpolygon

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.13. Self-contacts

Checks if the geometry has self contact points (in line or polygon), i.e., a vertex that touches more than two segments of the same ring. Self contacts are errors.

Fig. 24.9 Self-intersection vs self-contact.

See also

Self-intersections

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line, polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Self contact error points	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Self contact features Optional	OUTPUT	[same as input] Default: [Skip output]	Line or polygon layer containing self-contact features. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Self contact error points	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part where the self-contact occurs. gc_ringidx: the index of the ring where the self-contact occurs. gc_vertidx: the index of the vertex where the self-contact occurs. gc_errorx: the x coordinate of the self-contact. gc_errory: the y coordinate of the self-contact. gc_error UNIQUE_ID field: the unique ID of the self-contacting input feature.
Self contact features	OUTPUT	[vector: same as input]	Output polygon or line layer with features containing the self-contact features. If no self-contact features are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryselfcontact

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.14. Self-intersections

Detects self-intersections in line or polygon geometries, and reports them as errors. Self-intersections occur when the segments of a geometry cross over each other without having a common vertex.

Fig. 24.10 Self-intersection vs self-contact.

See also

Split self-intersecting geometries, Self-contacts

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line, polygon]	Layer with the geometries to check
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification
Self-intersecting errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Self-intersecting features Optional	OUTPUT	[same as input] Default: [Skip output]	Line or polygon layer containing self-intersected features. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Self-intersecting errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part where the self-intersection occurs. gc_ringidx: the index of the feature’s geometry ring where the self-intersection occurs. gc_vertidx gc_errorx: the x coordinate of the self-intersection. gc_errory: the y coordinate of the self-intersection. gc_error gc_segment_1: the index of the first segment involved in the intersection. gc_segment_2: the index of the second segment involved in the intersection. UNIQUE_ID field: the unique ID of the self-intersecting input feature.
Self-intersecting features	OUTPUT	[vector: line, polygon]	Output polygon or line layer with features containing the self-intersecting features. If no self-intersecting features are found, the output layer will be empty. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometryselfintersection

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.15. Small angles

Compares the angles within line or polygon geometries to a specified threshold, and reports as error any angle below that value.

Fig. 24.11 Reporting errors on a line feature for angles lower than 15°.

See also

Delete small angles

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line, polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Minimum angle	MIN_ANGLE	[numeric: double]	Allowed minimum angle between adjacent segments in a feature’s geometry. Any angle below this threshold is reported as error.
Small angle errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing the errors location. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Small angle errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part containing the small angle. gc_ringidx: the index of the feature’s geometry ring containing the small angle. gc_vertidx: the index of the vertex with the small angle in the feature’s geometry ring. gc_errorx: the x coordinate of the vertex with the small angle. gc_errory: the y coordinate of the vertex with the small angle. gc_error: the error angle value. UNIQUE_ID field: the unique ID of the input feature with the small angle.

Python code

Algorithm ID: native:checkgeometryangle

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.16. Small gaps

Checks for gaps between polygons in the input layer. Gaps with an area smaller than the gap threshold are reported as errors. If an allowed gaps layer is provided, the algorithm ignores gaps that fall entirely within polygons from this layer. An optional buffer can be applied to the allowed gaps.

Fig. 24.12 Reporting errors on polygon features for gaps smaller than the specified threshold.

See also

Fill gaps, Validate coverage

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Gap threshold	GAP_THRESHOLD	[numeric: double] Default: 0.0	Maximum area of gaps to be reported as errors, in map units. If set to 0, all the gaps are reported.
Allowed gaps layer Optional	ALLOWED_GAPS_LAYER	[vector: polygon]	Optional layer specifying polygons whose areas should be ignored during the gap check. Gaps that fall entirely within these polygons will not be reported as errors.
Allowed gaps buffer Optional	ALLOWED_GAPS_BUFFER	[numeric: double] Default: 0.0	Buffer distance to apply to the allowed gaps layer, in selected units. Gaps located within this buffered area are ignored. Allows adding a spatial tolerance around allowed gaps to avoid reporting near-boundary gaps as errors.
Neighbors layer	NEIGHBORS	[vector: table] Default: [Create temporary layer]	Specification of the output table representing the gap ID and the unique ID of its neighbor features. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Gap errors Optional	ERRORS	[vector: point] Default: [Skip output]	Specification of the output layer containing the centroid points of the gaps. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Gap features	OUTPUT	[vector: polygon] Default: [Create temporary layer]	Specification of the output layer containing the gap geometries. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Neighbors layer	NEIGHBORS	[vector: table]	A 1–N relational table, meaning that one gap can be associated with multiple neighboring polygons. The output table contains the following fields: gc_errorid: the ID of the gap. UNIQUE_ID field: the unique ID of an input feature that is a neighbor of the gap.
Gap errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of the centroid of the gap. gc_errory: the y coordinate of the centroid of the gap. gc_error: the area of the gap. gc_errorid: the ID of the gap.
Gap features	OUTPUT	[vector: polygon]	Output layer containing the gap geometries. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrygap

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.17. Small segments

Calculates length of individual segments in line or polygon geometries, and reports segments shorter than a minimum length as errors.

Fig. 24.13 Reporting errors (in red) on single line segments shorter than the given threshold.

See also

Delete features

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: line, polygon]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
Minimum segment length	MIN_SEGMENT_LENGTH	[numeric: double] Default: 0.0	Minimum length of segments to be considered valid, in map units.
Short segments errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing centroid of short segments. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Short segments features Optional	OUTPUT	[vector: same as input] Default: [Skip output]	Specification of the output layer for features containing short segments. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
Short segments errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx: the index of the feature’s geometry part containing the small segment. gc_ringidx: the index of the feature’s geometry ring containing the small segment. gc_vertidx: the index of the end vertex of the small segment in the feature’s geometry ring. gc_errorx: the x coordinate of the centroid of the small segment. gc_errory: the y coordinate of the centroid of the small segment. gc_error: the error segment length. UNIQUE_ID field: the unique ID of the input feature with the small segment.
Short segments features	OUTPUT	[vector: same as input]	Output layer containing, for each identified short segment, the feature it belongs to. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrysegmentlength

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

24.1.3.18. Strictly multipart

Checks if multipart geometries have more than one part. Multipart geometries with only one part are errors.

See also

Convert to strictly multipart

Parameters

Basic parameters

Label	Name	Type	Description
Input layer	INPUT	[vector: geometry]	Layer with the geometries to check.
Unique feature identifier	UNIQUE_ID	[tablefield: any]	Field storing unique values for feature identification.
One-part geometry errors	ERRORS	[vector: point] Default: [Create temporary layer]	Specification of the output layer containing centroid of the multipart geometries that have only one part. One of: Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
One-part geometry features Optional	OUTPUT	[vector: same as input] Default: [Skip output]	Specification of the output layer for features containing multipart geometries that have only one part. One of: Skip Output Create Temporary Layer (TEMPORARY_OUTPUT) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label	Name	Type	Description
Tolerance	TOLERANCE	[numeric: integer] Default: 8	Numerical precision of geometric operations, given as an integer n, meaning that two vertices less than 10-n apart (in map units) are considered to be merged.

Outputs

Label	Name	Type	Description
One-part geometry errors	ERRORS	[vector: point]	Output point layer representing the error locations and information. The output layer contains the following fields: gc_layerid: the ID of the input layer. gc_layername: the name of the input layer. gc_partidx gc_ringidx gc_vertidx gc_errorx: the x coordinate of the centroid of the multipart geometry that has only one part. gc_errory: the y coordinate of the centroid of the multipart geometry that has only one part. gc_error UNIQUE_ID field: the unique ID of the input feature that is multipart but has only one part.
One-part geometry features	OUTPUT	[vector: same as input]	Output layer containing features that are multipart but have only one part. Available fields are the same as in the ERRORS output.

Python code

Algorithm ID: native:checkgeometrymultipart

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.