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Hello - I have a dataset of polygons (some of which are donut polygons). Some of these polygons contain multiple parts (i.e. more than one polygon per record). When I run this dataset through an AreaOnAreaOverlayer it seems that some of the multiple polygon parts are lost. This is shown in a comparison of 'DataExtent.png' with 'AonA_Output_Extent.png'.

 

I have tried running the polygon dataset through a Deaggregator thinking this would split records with multiple geometries in to multiple records (in case multiple polygons per record was causing an issue for the AreaOnAreaOverlayer). However the output from the Deaggregator is untouched regardless of the settings in the transformer (so perhaps these are not aggregates).

 

Ultimately I need to run these polygons through the AreaOnAreaOverlayer but need all parts to be considered.

 

 

The data was initially stored in an Esri file geodatabase and I've also tried as a Mapinfo .TAB but am getting the same results. I have also included a link below to the data stored as a .shp file.

 

Apologies if I'm missing something obvious here but I'm really puzzled as these transformers are not behaving as I'd have expected. Any suggestions would be very gratefully received!

 

Thanks and all the best,

 

Matt

 

It doesn't look like you have valid geometries, if you test for OGC_VALID with the geometry validator you will see they all fail.

 

I'm not sure how these geometries have been created, visually it appears that they should be multiparts, but they seem to be some sort of inside out donuts, e.g. the feature with OBJECTID 6, its outershell appears in fact to be this hole

 

I would try to rebuild the geometries using a donut hole extractor followed by a donut builder (drop holes set to yes)

Hi @ebygomm - thanks for this suggestion - I'll give it a try and let you know how it goes.

Hi @ebygomm - your suggestion worked - thanks again for taking the trouble to reply. I really appreciate this..

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