Identify operation is intermittent on Oracle Spatial geodetic feature classes

Description

Cause

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.

Workaround