Skip to main content
  • EN

I have a dataset of around 85k road segments and 130k non-road segments where I want to cut off small parts of the roads around the non-road segments: There's a buffer around each of the non-road segments that I use as clipper on the roads.

I've applied all the tips given in this thread ( https://knowledge.safe.com/questions/62461/why-the-clipper-transformer-is-too-slow.html ). I forced the clipper to wait until all clippers were available, I dissolved both datasets before clipping and it works fine on smaller datasets. Still, it takes around 2 seconds per feature in the dissolved dataset (total 12k). I've even discarded all attributes.

Algorithmically, clipping polygons should take nowhere near as long when everything fits in memory. [M. de Berg et al. Computational Geometry. Ch2 ]

Is there anything I've missed? Why is clipping so slow?

Contrary to the advice given in the other thread, I've found that not dissolving the features before the clipper is faster. It now took ~90 seconds, instead of hours.

 

This may be because now the locality is preserved, so it isn't compared to all other polygons, though that is only my hypothesis, I can't see the inner workings of FME.

 

 

Contrary to the advice given in the other thread, I've found that not dissolving the features before the clipper is faster. It now took ~90 seconds, instead of hours.

 

This may be because now the locality is preserved, so it isn't compared to all other polygons, though that is only my hypothesis, I can't see the inner workings of FME.

 

 

Hi @arjanboogaart That other thread is already dated as we're overhauling the Dissolver now. Which build of FME are you using?

 

I'd also consider pumping the non-dissolved buffered non-road folks into the LineOnAreaOverlay as the areas, and the roads in as lines. That method will employ a good spatial index underneath. You shoudl be able to tell the lines that were in vs. out by checking their overlap count afterwards.

Community Stats

31,840
Posts
120,936
Replies
39,474
Members

Latest FME

Terms & ConditionsCookie settings
A product of
Safe Software respectfully acknowledges that we live, learn and work on the traditional and unceded territories of the Kwantlen, Katzie, and Semiahmoo First Nations.