Hi @mercedes, this transformer is not available via the gallery or FME hub, so it is difficult to answer your question. Is it by any chance a custom transformer?

just calculate area and then do an overlay with areaonarea etc., clipper etc. and calculate resulting area's.

Then you have both area-values and overlap attribute to calculate the percentage of overlap.

For total overlap per ID you can use the statisticscalculator with group by attribute. etc.

It's an old transformer written a while back by a colleague of mine at 1Spatial. It should work in an older FME as I believe it was written in FME 2013. However, as we haven't yet published it formally to the Hub it is supplied below "as-is" to see if its of interest to you.

percentoverlap.fmx

Details from the help:

Returns the % of overlap between geometries.

This transformer assumes that INPUT features are geometry-based features.

Raster, pointcloud, surface, solid, collection and null features will be REJECTED.

3D components will be ignored.

OUTPUT features will have a new attribute appended which by default is named overlappercent but which can be customised by the user via the transformer's parameters.

Note: This will NOT tell you which candidate features overlap a set of features by how much. It will only tell you how much each feature is overlapped by all other features in the dataset.