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Question

How to remove “Self intersections” Polygons using FME


ahmad_saleh
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How to remove “Self intersections” using FME

 

 

I wonder if there is a method to repair the self-intersections in the FME such as the ArcGIS tools “(Check geometry and repair geometry).

 

 

I have used GeometryValidator but it fails to repair the polygons, What might be the issue here ?

 

 

 

 

Regards,

 

Ahmad Saleh 

4 replies

david_r
Celebrity
  • July 28, 2015
Hi

 

 

I suggest you send one of the failing polygons to the Data Inspector and check carefully, vertex by vertex. Is it possible that the polygons have other, more serious problems than self-intersections?

 

 

David

nielsgerrits
VIP
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The GeometryValidator is a possible tool to repair 2D selfintersections. It just replaces the originaly feature by an aggregate of features split on former intersections.

 

 

There is no simple solution like the repair geometry tool. In FME you need to understand the problem to solve it.

 

 

Best practices:

 

- Putting a ListExploder and then a VertexCreator after the GeometryValidator Failed port really helps to display the location of the problems. Often there is more then one problem within a feature.

 

- Be aware that the order of Checks do influence the results.

 

- Repaired features must be checked again with another GeometryValidator.

 

 

ahmad_saleh
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Thanks David and Niels,

 

Both of your suggestions helped me to find the location of the error and I have avoided it by adding bufferer tool before the clipper then the issue of having the 2d self-intersection was gone and there is no need to repair it, but I couldn’t figure it out without your help.

 

 

 

Many thanks guys,

 

Best regards,

 

Ahmad

I had the same issue. I fixed it by adding a GeometryValidator to repair the self intersections, but followed by a deaggregator because the GeometryValidator doesn't seem to deaggregate the polygon. Then aggregate them back up if you need afterwards. My output was JSON . Without the deaggregator it was creating a 'GEOMETRYCOLLECTION' which isn't supported by a lot of web apps, whereas when you add the deaggregator and aggregator it back up afterwards it creates a MultiPolygon json type which is supported better.


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