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AreaOnAreaOverlayer: Creating Two Features/Attributes within Overlapping Polygons

  • June 21, 2019
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Hello,

I have two polygon layers:

Layer 1 contains approx 2500 polygons some of which overlap with each other.

Layer 2 contains approx 150,000 polygons which have been clipped so that all features are inside at least one Layer 1 polygon.

I would like to intersect the Layer 2 features so that they are given the attributes (essentially a polygon ID) of the Layer 1 polygon that they fall within, and if a polygon falls within a Layer 1 overlap then two new polygons are created, one for each Layer 1 polygon it fell within.

I thought that AreaOnAreaOverlayer would achieve this but when two Layer 1 polygons overlap it only outputs a single Layer 2 polygon (I don't know how it decides which attribute to give it). Perhaps Intersector would be a more appropriate Transformer to use (and it is the equivalent tool that I would use in ArcMap). I don't know. Although I'm getting an error when trying that Transformer which would need to be addressed outside the focus of this question.

Both layers are polygons but if it helps, think of Layer 2 as a linear network.

I'm new to FME and absolutely loving it's functionality so far. I will be very grateful for any help you can give me.

Thank you

 

 

Best answer by ebygomm

I think the AreaOnAreaOverlayer will do what you want, but to get two polygons output you will need to generate a list in the AreaOnAreaOverlayer and then explode it

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ebygomm
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  • June 21, 2019

I think the AreaOnAreaOverlayer will do what you want, but to get two polygons output you will need to generate a list in the AreaOnAreaOverlayer and then explode it


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  • June 22, 2019

I think the AreaOnAreaOverlayer will do what you want, but to get two polygons output you will need to generate a list in the AreaOnAreaOverlayer and then explode it

It works, thank you! Seems obvious now but I hadn't fully understood the purpose of generating lists. To be clear for future readers, I enabled the Generate List parameter then sent the results to the List Exploder transformer.

In addition I then ran it through a Tester because I didn't require the Layer 1 intersections, only those from Layer 2.

Much appreciated - now onto the next problem...