Question

Spatial relation seems to struggle with boundary coordinates

  • 25 October 2022
  • 3 replies
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An overlay analysis between some polygons and a few lines has turned into quite the ordeal.

I hope the supplied workspace and data is self-explanatory.

In it there is four tests that yield different results.

I start with clipping the lines with the polygons followed by a spatial relator intended on creating a list of references. I would expect that relator would find a relation between all lines since they can only be INSIDE. But more than half fails.

To test the reason I run it through an Intersector and measure the distance from intersection node to polygon mask. I guess that is supposed to be 0, but 3 of 20 return a value larger than 0 - meaning that the intersectionnode is not in the intersection.

 

 

 


3 replies

Badge +20

Everything comes down to geometry precision.

SpatialRelator and SpatialFilter don't have a Tolerance parameter.

This should be a known issue.

Badge +2

@mathiku​ As @caracadrian​ mentions - the SpatialRelator / SpatialFilter do not have a tolerance so you have to make sure your lines and areas have nodes or vertices where they touch. TopologyBuilder is usually your friend for doing this. See the attached workspace (FME 2022)

Badge +2

Everything comes down to geometry precision.

SpatialRelator and SpatialFilter don't have a Tolerance parameter.

This should be a known issue.

An issue? It's an error. It doesn't follow OGC-compliance.

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