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Super Contributor
Posts: 419
Registered: ‎10-12-2015

Understanding Feature Type Point, Line and Area and using CompoundGeometry

Until recently some of my customers reguarly set Feature Type to 'GeometryCollection' when the source geometry type was 'CompoundGeometry'.

It was recently explained to me that Feature Type 'GeometryCollection' is not for use with 'CompoundGeometry' but is instead a mechanism for ensuring symbolizers are strictly applied based on source geometry type - an sort of filter. 

Setting type to 'GeometryCollection' has an impact on the rendering process because if this type is enabled, then the expected behaviour is that:
- Points will be rendered by PointSymbolizers
- Lines by LineSymbolizers
- Polygons by PolygonSymbolizers
- and Text by TextSymbolizers

For example, text label will only display if the geometry type is actually text. Point, line and area geometries therefore can't have a label added in that situation.

So my understanding is roughly


(Looks like geometrymath is excluded - appears can apply geometry math and you can then still symboloize points for area or lines geometries).


Anyway, I then started looking at which Type should be used for 'CompoundGeometry'. i.e. a feature class where geometry has points, lines and polygons. The documentation indicated that the Feature Type chosen should correspond to the geometry type, if I read it correctly.


I then discovered that it didn't mater which type I set it to (Point, Line, Area), it behaved the same in the map. 

I then took a point feature and changed the type to Area and it behaved the same in the map.


So I'm wondering

  • Is there a recomendation of which feature type to set for CompoundGeometries?
    When adding a new feature that uses CompoundGeometry from database I observe the system sets the type to Point. I currently change it to Area - is that best?
  • What is the purpose of having different 'Point', 'Line' and 'Area' types, I'm struggling to observe the difference - perhaps I havn't run the right experiement yet or didn't observe a subtle difference.