Identify operation is intermittent on Oracle Spatial geodetic feature classes

Last Published: April 25, 2020


** Internal Publish Only! This article may contain information that is not intended for external circulation. **

Identify operations in ArcCatalog or ArcMap sometimes return no features or the wrong features.


A filter shape is generated based on the pointer position on the display when performing the Identify operation in ArcGIS. The spatial filter shape is created using the coordinate system of the display and converted to the coordinate system of the data. While the cursor may appear to be close to the geodetic feature in the display, in real world units, it may not be.

The reason is Oracle Spatial geodetic data represents geometry with angular coordinates, for example latitude and longitude. Straight line segments connecting the vertices are assumed to follow a great circle path. Depending on the projection used to display the geometry, the great circle path my not lie on the same straight line path shown on the display. The further apart the vertices are, the greater the possible divergence.

Identify operations may fail because the display representation of geodetic features, using projected straight line boundary segments, differs significantly from the geodetic representation that assumes boundary segments follow great circle paths between vertices. This issue can also affect spatial selections and zooming; operations which use spatial queries to determine what features to return from the database. One method to verify these types of failures is to place the cursor near a vertex of the line or polygon and identify again. If the Identify operation works near a vertex more often than between widely-spaced vertices, then this is likely the cause.


Geodetic (spherical) polygon and line data cannot be displayed with complete accuracy using a planar coordinate system. One solution is to densify the geodetic features, creating additional vertices between widely spaced vertices. Reducing the distance between vertices can mitigate the divergence of the feature representation on the screen from the spatial index’s interpretation of the geometry’s boundary line segments.

Also, please note that Oracle SDO_GEOMETRY geodetic features may not contain any line segments that extend over one half the circumference of the Earth or polygons that have an area greater than one half the area of the Earth’s surface. Such feature may cause display and spatial indexing problems.

    Article ID:000007647

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