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Question

Lineonlineoverlay - exclude self-intersections


Forum|alt.badge.img+1

Hello,

I am using LineOnLineOverlay to detect intersections within a polyline dataset. I am only interested in intersection points that involve more than one feature, and would therefore like to exclude any intersection points where a feature is intersecting against itself.

Using the attached image as an example; I wish to ignore the intersection where line A is intersecting itself, but need to record where lines A and B intersect, and where line C crosses over line B.

TIA,

RB

 

4 replies

jdh
Contributor
Forum|alt.badge.img+28
  • Contributor
  • May 15, 2019

What about assigning each feature a unique ID and then use a topologyBuilder. You can examine the node list to identify which nodes have multiple edges and whether they were part of the same feature originally.


sammy
Supporter
Forum|alt.badge.img+17
  • Supporter
  • May 7, 2025

Here is the idea to upvote requesting this functionality in the LineOnLineOverlayer transformer:

 


raghavendrans
Enthusiast
Forum|alt.badge.img+14

@robinb 

Have you explored looking at the _overlaps value of the point features coming out of the “Point” output port of the LineOnLineOverlayer?

Happy FME:-) ing

Cheers

SRG


takashi
Influencer
  • May 8, 2025

Hi ​@robinb ,

LineOnLineOverlayer split input lines at their intersections including self-intersections, but self-intersection points won't be output from the Point port. So, I think you can get required result by using the points output from the Point port of LineOnLineOverlayer to split the original lines again with PointOnLineOverlayer. The data flow looks like this.

Split Lines at Intersections excluding Self-Intersections

 


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