Check Geometry

Overview

The Check Geometry tool scans input vector features for geometry quality issues and outputs an issue list table. The tool does not modify input features and does not automatically repair issues. It is mainly used for quality checks before data loading, spatial analysis, and map production.

The check results record the feature identifier, problem type, and problem description for each issue, making it easier to review issues manually or process them with the Repair Geometry tool.

How It Works

The tool checks the geometry field of each input feature and identifies the following issues:

Problem type	Check	Output description
Empty geometry	The geometry value is empty or missing.	ProblemType is Empty geometry.
Empty geometry object	The geometry object exists but has no coordinates.	ProblemType is Empty geometry object.
Invalid geometry	The geometry does not meet Shapely/OGC validity rules.	Description records the underlying validity message, such as a self-intersection location.
Duplicate vertex	Adjacent vertex coordinates are exactly the same.	Records the approximate location of the duplicate vertex.
Unclosed ring	The first and last coordinates of a polygon feature's exterior ring are different.	Mainly used for abnormal polygon ring structures.
Short segment	A segment length is smaller than Segment length tolerance.	Description records the detected segment length.
Empty Z value	A 3D geometry contains a NaN or empty Z coordinate.	Used to identify missing elevation values in 3D features.
Incorrect envelope	The geometry envelope extent does not match the geometry extent.	Used to detect abnormal geometry extents.

The output table contains three columns: FeatureID, ProblemType, and Description.

Use Cases

• Quality check before data loading: check geometry anomalies in supplier data, field-collected data, or historical deliverables.
• Precheck before spatial analysis: reduce the probability that overlay, clipping, buffer, spatial join, and other tools fail because of invalid geometry.
• Inspection after editing: confirm that manual editing, batch processing, or format conversion has not introduced duplicate vertices, empty geometry, or similar issues.
• 3D data check: find empty elevation values in geometry with Z values.

Parameters

Parameter	Description	Notes
Input vector file	Vector feature dataset to check.	Required. Supports point, line, polygon, and multipart geometry.
Segment length tolerance	Threshold used to identify short segments.	Required. Default: 1e-16. Units are the same as the input feature coordinate system.
Output table file	Output issue list table.	Required. Supports table output formats.

Output

The output is a table. If issues are found, each row represents one type of geometry issue for one feature:

Field	Meaning
FeatureID	Index of the input feature with an issue.
ProblemType	Problem type, such as Invalid geometry, Duplicate vertex, or Short segment.
Description	Problem description or explanatory information returned by the underlying geometry library.

If the output table is empty, no issues were found under the current check rules and tolerance settings.

Steps

1. Start the tool: Open Geoprocessing Toolbox > go to Vector tools > Feature processing > Build > open the Check Geometry tool pane.
2. Set the input: Select the Input vector file to check.
3. Set the tolerance: Set Segment length tolerance based on the data precision. In most cases, the default value can be used.
4. Configure the output: Set the path and name for the Output table file.
5. Run the check: Click Run. After completion, open the output table and review ProblemType and Description.
6. Handle issues: Based on the problem type, decide whether to edit manually, recollect data, delete abnormal features, or run Repair Geometry.

Notes

• This tool only discovers issues and does not automatically repair them. To repair issues, use the Repair Geometry tool.
• Segment length tolerance units are the same as the coordinate system. In a geographic coordinate system, the unit is degrees. In a projected coordinate system, the unit is usually meters.
• FeatureID uses the input feature index and may not be the same as the ID in a business field or OBJECTID.
• The current check rules cover common geometry issues but are not equivalent to a complete topology rule check. For example, gaps and overlaps between adjacent polygons require topology tools.
• After repair, run this tool again to confirm that the issue list is empty or meets quality requirements.