Question

Differences between self-intersections in GeometryValidator

  • 14 February 2022
  • 2 replies
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Hi!

 

I'm validating the quality of the CityGML and CityJSON building datasets. I'm wondering what is the real difference between all self-intersection rules implemented in the FME's GeometryValidator.

 

So shortly: Is the rule Self-Intersection in 2D same as the Self-Intersection under the OGC Valid and OGC Simple?

 

I think I understand the difference between Ring Self-Intersection, Surface Self-Intersect and Shells Intersect at least. Still, I would be grateful for proper definitions of all these errors. The document of GeometryValidator is a little bit unclear in the case of these "sub-errors".

 

Thank you a lot!


2 replies

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@alpoturunen​ Thanks for you comment - we can always improve our documentation and will take another look at the GeometryValidator to try and clarify the different rules.

The for self intersection, fundamental difference is the limited geometry support for OGC. For example, OGC geometries do not support arcs. In earlier versions of GeometryValidator, FME would stroke arcs and then try and validate. Since an arc is an invalid OGC geometry, GeometryValidator will now result in a failed test if an FME feature includes an arc geometry.

So really, OGC Compliant and OGC Simple should be used for geometries that need to confirm to OGC requirements.

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Thank you a lot !

 

I have a few similar question.

 

How about the Surface Wrong Orientation (under the Invalid Solid Boundaries) and the Incorrect Surface Orientation? Is there any difference between these two rules?

 

And is the Repeated Points (under the OGC Simple) same as the Duplicate Concecutive Points?

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