ChangeDetector

From Fmepedia

ChangeDetector is a Workbench Transformer. Detects changes between two sets of input features. One set of features enters the transformer via the ORIGINAL port. The other set enters via the REVISED port.

An ORIGINAL feature is output via the UNCHANGED port when it is found to have either matching geometry, matching attribute values, or both, with a feature in the REVISED set.

An ORIGINAL feature is output via the DELETED port when no match for it can be found in the REVISED set.

A REVISED feature with no match in the ORIGINAL set is output via the ADDED port.

If Lenient Geometry Match is set to yes, then the order of points in area features will be ignored.

If Treat Blank Value as Different From Missing Attribute is Yes, then an attribute will be considered different for two features when one feature contains the attribute with a blank value and the other feature does not contain the attribute at all.

When geometry is being matched, Extra Vertex Tolerance can allow for extra vertices along line segments. A value of 0 means that no such extra vertices are permitted. A nonzero value controls how close any extra vertices must be to the line connecting the adjoining matching vertices. Note: This setting has no effect when using lenient geometry matching.

The Matcher provides a more general approach, which may be more convenient for certain applications.

There is no way to have the ChangeDetector output updated features (i.e. features which have the same ID in both the ORIGINAL and REVISED datasets, but differ in geometry). However, you can use a Matcher to see if a NEW feature ID matches a DELETED feature ID, if so it must be an edit not an addition.