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Check if Polygons are equal in SDE

Question asked by SuperLoehr on Jan 19, 2016
Latest reply on Jan 20, 2016 by vangelo-esristaff



I have a problem with comparing polygon objects in an (Oracle)SDE.


I have to compare two polygon feature classes that contain the same data from different points in time.

Featureclass "A" contains the "official" polygons from a local government and is delievered to us on a 3-month basis.

Featureclass "B" contains the same set of polygons, but some of them may have been edited by our client.

The total amount of polygons is always the same and they share one ID so that you can always find the "partner" objects in the two sets.


The job is to find all the polygons that have geometric differences between the two sets.


This could be done with ST_Equals or ST_Relate or ST_SymmetricDiff and I tried all of them.


The Problem:

The featureclass that was edited by my client has been processed in a workflow that includes some topology operations.

During that topology geoprocessing ArcGIS inserts additional vertices in nearly every polygon to be able to conduct the operations.

See the part "Note" at ArcGIS Help (10.2, 10.2.1, and 10.2.2)

Those vertices don't change the geometry of the polygon because they are inserted in the middle of straight border lines.


If you compare the sets "A" and "B" with ST_Equals or ST_Relate or ST_SymmetricDiff after one of them has been "treated" by the topology geoprocessing, there are thousands of "differences" although the polygons aren't really changed but only contain additional vertices.


Is there a way to compare polygons while ignoring those additional vertices?

One limitation: It needs to be done within an SQL statement on the SDE.


Thanks for any Idea!