Polygon Overlap is Sliver—ArcGIS Pro

Available with ArcGIS Pro Standard and Data Reviewer licenses.

Summary

Sliver polygons are usually small polygons resulting from overlay operations such as Intersect or Union. Sliver polygons typically have an area that is much smaller than the perimeter. The Polygon Overlap is Sliver check finds overlaps between polygon features that are below a specified thinness ratio.

Supported workflows

ArcGIS Data Reviewer checks support multiple methods for implementing automated review of data. The following table identifies the supported implementation methods for this check:


Workflow	Supported	Licensing
Validation attribute rule	Yes (ArcGIS Pro 2.9 and ArcGIS Enterprise10.9.1 or later)	Available with ArcGIS Pro Standard and Data Reviewer license
Constraint attribute rule	No	N/A
Run Data Checks	Yes (ArcGIS Pro 3.5 or later)	Available with Data Reviewer license

Overview

The Polygon Overlap is Sliver check finds overlaps between polygon features that are slivers based on their shape and, optionally, size. Sliver overlaps between polygon features often result from creating polygon features without proper snapping settings or from editing shared boundaries without a topology.

When configured as a validation rule, an error is created for each feature that shares a boundary with a sliver overlap.

Attribute Rule syntax

The following table describes the validation attribute rule parameters:


Parameter	Required	Description	Workflow
Subtype	No	The subtype(s) to which the rule is applied.	Validation
Attribute	No	A query that identifies the features to which the rule is applied.	Validation
Features to Compare	Yes	Input features are returned as errors based on their relationship to the features from this data source. Only polygon features are supported.	Validation
Filter	No	A query that identifies the features to include in the rule, from the data source specified in the Features to Compare parameter.	Validation
Thinness Ratio	Yes	The thinness ratio (T) between the overlap area (A) and its perimeter (P) is calculated using the following equation: `T = 4π(A/P²)` A thinness ratio of 1 is a perfect circle and a thinness ratio of 0 is a line. Overlaps between polygons with a thinness ratio less than this value are considered errors.	Validation
Maximum Area	No	The maximum overlap area that is considered a sliver overlap. Overlaps between polygons that are below the thinness ratio and equal to or less than this value are considered errors. The default unit of measure is the unit of measure used by the input data source's horizontal spatial reference.	Validation
Name	Yes	A unique name for the rule. This information is used to support data quality requirement traceability, automated reporting, and corrective workflows.	Validation
Description	No	A description of the error you define when a noncompliant feature is found. This information is used to provide guidance for corrective workflows.	Validation
Severity	No	The severity of the error assigned when a noncompliant feature is found. This value indicates the importance of the error relative to other errors. Values range from 1 to 5, with 1 being the highest priority and 5 being the lowest.	Validation
Tags	No	The tag property of the rule. This information is used in rule authoring and management workflows to support traceability and reporting of data quality requirements.	Validation

Run Data Checks syntax

The following table describes the Run Data Checks parameters:


Parameter	Required	Description
Input Feature	Yes	The input feature layer that is evaluated by the rule. Note: You can disable a map selection or layer definition query using the toggle button that honors the selection or filter before evaluation. Layer definition queries that include a spatial clause are not supported.
Attribute Filter	No	A query that identifies the features to which the rule is applied.
Features to Compare	Yes	Input features are returned as errors based on their relationship to the features from this data source. Only polygon features are supported. Note: You can disable a map selection or layer definition query using the toggle button that honors the selection or filter before evaluation. Layer definition queries that include a spatial clause are not supported.
Filter	No	A query that identifies the features to include in the rule, from the data source specified in the Features to Compare parameter.
Thinness Ratio	Yes	The thinness ratio (T) between the overlap area (A) and its perimeter (P) is calculated using the following equation: `T = 4π(A/P²)` A thinness ratio of 1 is a perfect circle and a thinness ratio of 0 is a line. Overlaps between polygons with a thinness ratio less than this value are considered errors.
Maximum Area	No	The maximum overlap area that is considered a sliver overlap. Overlaps between polygons that are below the thinness ratio and equal to or less than this value are considered errors. The default unit of measure is the unit of measure used by the input data source's horizontal spatial reference.
Name	Yes	A unique name for the rule. This information is used to support data quality requirement traceability.
Extent	Yes	Visible Extent—Evaluate the visible extent of the map. Full Extent—Evaluate the full extent of the data.

Notes

Keep the following in mind when using the check:

The data sources of the input features and Features to Compare parameter must share a common datum.
Learn more about spatial references
The Validation Status attribute values of both the input features and the data sources included in the Features to Compare parameter are ignored during evaluation. For example, input features with a validation status of 0 (No calculation required, no validation required, no error), 1 (No calculation required, no validation required, has error(s)), 4 (Calculation required, no validation required, no error), or 5 (Calculation required, no validation required, has error(s)) are still included during rule evaluation.
The Attribute and Filter parameters are limited to comparison (=, <>, >, <, >=, and <=) and logical (AND/OR, IN/NOT IN, LIKE/NOT LIKE, and IS NULL) operators.
Data sources for the Features to Compare parameter must include a global ID field.
Errors are returned for overlaps that are greater than the x,y tolerance of the spatial reference.
Include the data source for the Features to Compare parameter when creating map or project packages and when sharing web layers with the Validation capability enabled.
The Attribute and the Features to Compare filter parameters do not support the following field types: Big Integer, Date Only, Time Only, and Timestamp Offset. If selected, the row header is marked in red and does not allow the rule to be saved.