To put it simply, I have created a model which takes a single candidate polygon and compares with a number of potentially overlapping clipper polygons from a database. This has run on FME Flow for a few months now without issue, however a recent combination of polygons has caused an output I cannot get my head around.
I have isolated the issue to a very small model, consisting of one shapefile with three Clipping polygons and another shapefile of a single candidate polygon (see data attached).
Model:
Candidate Polygon:
Clipper polygons (note the smaller polygons overlapping the larger one, totalling three):
When fed into a Clipper transformer, I would expect three results. One for each clipper where it overlaps with the candidate. Instead I get the following:
Result 1:
Result 2:
Result 3 (a donut is formed with the middle polygon by the smallest clipper polygon):
The first and second of the above outputs are expected, but the third forms a donut with the smallest polygon. I’ve tried many different settings and followed what guidance there is but I cannot understand why this donut is being created.
Of the below image I would expect an output similar to Clip Original Candidates. This is the setting I’ve used for my clipper.
It seems as though the clippers are clipping each other, or the Clip Original Candidates setting is only applying to the first input clipper.
Any help here would be greatly appreciated.