Solutions for topology errors

When you use the S-58 Error Manager tool to validate products in your maritime database, results are reported and grouped according to severity as well as the specific type of error. Some of those errors can be topology-related and could impact multiple maritime features. There are several ways to correct topology errors. Different error types have different solutions available for them. The following error types and their solutions are presented:

• Overlapping polygons
• Rule violations for Must Be Covered By
• Self-overlapping features

Overlaps

The following image shows S-58 error 42 Group 1 coverage is not correct, a hole or an overlap exists, where both DEPARE as well as DEPCNT features are flagged due to an overlap of a DEPARE polygon feature.

Errors caused by overlapping polygons can be realigned, merged into one of the polygons, subtracted from both, and turned into a separate new polygon feature. The Align Edge tool can be used to reshape the overlapping DEPARE topology edge to match and be coincident with the neighboring DEPARE topology edge, as shown in the following image.

Must Be Covered By

The following image shows S-58 errors 42 Group 1 coverage is not correct, a hole or an overlap exists and 519a Skin of the earth (Group 1) objects do not cover the data coverage (M_COVR=1), where a DEPARE feature is missing and therefore not covering the M_COVR polygon feature.

Errors caused by Rule violations for Must Be Covered By, can be fixed by creating a feature. You can specify a new DEPARE feature from the Create Features pane and use the Trace tool to create a feature, as shown in the following image.

Must Not Self Overlap

The following image shows error 40—Linear objects with the same class, attribute values which are connected and are not chained together, where a FERYRT is self-overlapping.

Errors caused by a self-overlapping feature can be fixed by deleting the extraneous vertex through the Edit Vertices tool.

This can also be accomplished in other ways, including editing within the Modify Features pane or manually removing through the context menu.

The following image shows editing within the Modify Features pane.

The following image shows manually removing the extraneous vertex through the context menu.