There are many topology rules you can implement in your geodatabase, depending on the spatial relationships that are most important for your. Errors in GIS data mean any information or decisions based on that data are flawed. Geodatabase topology provides an automated, rule-based solution to. Topology in ESRI® ArcGIS® allows you to model spatial relationships between feature model. Topology errors are violations of the rules that you can easily.
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There are many topology rules you can implement in your geodatabase, depending on the spatial relationships that are most important for your organization to maintain. You should carefully plan the spatial relationships you will enforce on your features. Some topology rules govern the relationships of features within a given feature classwhile others govern the relationships between features in two different feature classes or subtypes. Topology rules can be defined between subtypes of features in one or another feature class.
This could be used, for example, to require street features to be connected to other street features at both ends, except in the case of streets belonging to the cul-de-sac or dead-end subtypes. Many topology rules can be imposed on features in a geodatabase.
A well-designed geodatabase will have only those topology rules that define key spatial relationships needed by an organization. Most topology violations have fixes that you can use to correct errors.
Some topology rules, however, have no predefined fixes. Once you have discovered the topology errors, you can select the error on the map with the Fix Topology Error toolor select the error from within the Error Inspector. To view this document, you need a copy of Adobe Reader. Requires that a feature does not collapse during a validate process.
This rule is mandatory for a topology and applies to all line and polygon feature classes. In instances where this rule is violated, the original geometry is left unchanged. The Delete fix removes polygon features that would collapse during the validate process based on the topology’s cluster tolerance.
Any polygon feature, such rulds the one in red, that would collapse when validating the topology is an error. Requires that the interior of polygons not overlap. The polygons can share edges or vertices.
This rule is used when an area cannot belong to two or more polygons. It is useful for modeling administrative boundaries, such as ZIP Codes or voting districts, and mutually exclusive area classifications, such as land cover or landform type. The Subtract fix removes the overlapping portion of geometry from each feature that is causing the error and leaves a gap or void in its place. This fix can be applied to one or more selected Must Not Overlap errors. The Merge fix adds the portion of overlap from one feature and subtracts it from the others that are violating the rule.
You need to pick the feature that receives the portion of overlap using the Merge geodataase box. This fix can be applied to one Must Not Overlap error only. The Create Feature fix creates a new polygon feature out of the error shape and removes the portion of overlap from each of the features, causing the error to create a planar representation of the feature geometry.
This rule requires that there are no voids within a single polygon or between adjacent polygons. All polygons must form a continuous surface. An error will always exist geodatabasee the perimeter of the surface. You can either ignore this error or mark it as an exception. Use this rule on data that must completely cover an area.
For example, soil polygons cannot include gaps or form voids—they must cover an entire area.
The Create Feature fix creates new polygon features using a closed ring of the line error shapes that form a gap. This fix can be applied to one or more selected Must Not Have Gaps errors. If you select two errors and use the Create Feature fix, the result will be one polygon feature per ring.
If you want one multipart feature as a result, you will need to select each new feature and click Merge from the Editor menu. Note that the rulez that forms the outer bounds of your feature class will be in error. Using the Create Feature fix for this specific error can create overlapping polygons.
Remember that you can mark this error as an exception. You can use Create Feature to create a ruels polygon in geodtaabase void in the center. You can also use Create Feature or mark the error on the outside boundary as an exception.
Requires that the interior of polygons in one feature class or subtype must not overlap with the interior of polygons in another feature class or subtype. Polygons of the two feature classes can share edges or vertices or be completely disjointed. This rule is used when an area cannot belong to two separate feature classes. It is useful for combining two mutually exclusive systems of area classification, such as zoning and water body type, where areas defined within the zoning class cannot also be defined in the water body class and vice versa.
The Subtract fix removes the overlapping portion of each feature that is causing the error and leaves a gap or void in its place. This fix can be applied to one or more selected Must Not Overlap With errors. This fix can be applied to one Must Not Overlap With error only.
Requires that a polygon in one feature class or subtype must share all of its area with geodatabasf in another feature class or subtype. An area in the first feature class that is not covered by polygons from the other feature class is an error.
This rule is used when an area of one type, such as a state, should be completely covered by areas of another type, such as counties. The Subtract fix removes the overlapping portion of tules feature that is causing the error so the boundary of each feature from both feature classes is the same. The Create Feature fix creates a new polygon feature out of the portion of overlap from the topollogy polygon so the boundary of each feature from both feature classes is the same.
Requires that the polygons of one feature class or subtype must share all of their area with the polygons of another feature class or subtype. Polygons may share edges or vertices.
Any area defined in either feature class that is not shared with the other is an error. This rule is used when two systems of classification are used for the same geographic area, and any given point defined in one system must also be defined in the other.
One such case occurs with nested hierarchical datasets, such as census blocks and block groups or small watersheds and large drainage basins. The rule can also be applied to nonhierarchically related polygon feature classes, such as soil type and slope class. This fix can be applied to one or more selected Must Cover Each Other errors. Requires that polygons of one feature class or subtype must be contained within polygons of another feature class or subtype.
Any area defined geodatbase the contained feature class must be covered by an area in the covering feature class. This geoadtabase is used when area features of a given type must be located within features of another type. This rule is useful when modeling aarcgis that are subsets of a larger surrounding area, such as management units within forests or blocks within block groups.
This fix can be applied to one or more selected Must Be Covered By errors. Requires that boundaries of polygon features must be covered by lines in another feature class. This rule is used when area features need to have line features that mark the boundaries of the areas. This is usually when the areas have one set of attributes and their boundaries have other attributes. For example, parcels might be stored in the geodatabase along with their boundaries.
Each parcel might be defined by one or more line features that store information about their length or the date surveyed, and every parcel should exactly match its boundaries. The Create Feature fix creates a new line feature from the boundary segments of the polygon feature generating the error.
ArcGIS Desktop Help – Topology rules
Requires that boundaries of polygon features in one feature class or subtype be covered by boundaries of polygon features in another feature class or subtype. This is useful when polygon features in one feature class, such as subdivisions, are composed of multiple polygons in another class, such as parcels, and the shared boundaries must be aligned.
Requires that a polygon in one feature class contain at least one point from another feature class. Points must be within the polygon, not on the boundary. This is useful when every polygon should have at least one associated point, such as when parcels must have an address point.
The Create Feature fix creates a new point feature at the centroid of the geodatagase feature that is causing the error. The point feature that is created is guaranteed to be within the polygon feature. This fix argcis be applied to one or more selected Contains Point errors. The rues polygon is an error because it does not contain a point. Requires that each polygon contains one point feature and that each point feature falls within a single polygon.
This is used when there must be a one-to-one correspondence between features of a polygon feature class and features of a point feature class, such as administrative boundaries and their capital cities.
Each point must be properly inside exactly one polygon and each polygon must properly contain exactly one point. The top polygon is an error because it contains more than one point. Points are errors topoloby they are outside a polygon.
The Delete fix removes line features that would collapse during the validate process based on the topology’s cluster tolerance.
Any line feature, such rulws these lines in red, that would collapse when validating the topology is an error. Requires that lines topklogy overlap with lines in the same feature class or subtype. This rule is used where line segments should not be duplicated, for example, in a stream feature class. Lines can cross or intersect but cannot share segments. The Subtract fix removes the overlapping line segments from the feature causing the error. You must select the feature from which the error will be removed.
If you have duplicate line features, select the line feature you want to delete from the Subtract dialog box. Note that the Subtract fix will create multipart features, so if the overlapping segments are not at the end or start of a line feature, you might want to use the Explode command on the Advanced Editing toolbar to create single-part features.
This fix can be applied to one selected Must Not Overlap error only. Requires that line features from the same feature class or subtype not cross or overlap each other.
Lines can share endpoints. This rule is used for contour lines that should never cross each other or in cases where the intersection of lines should only occur at endpoints, such as street segments and intersections. This fix can be applied to one Must Not Intersect error only.