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How can I buffer outside a polygon only?

  • 31 March 2023
  • 6 replies
  • 31 views
H

I have have a set of polygons (actually they are buffers of a point) and I want to buffer these again to leave a ring - just keeping the buffer outside the original polygon. I can do this easily in arc/arcpy by using the buffer type "OUTSIDE_ONLY". How can I get the same effect using FME? I have created the buffers but when I use the clipper to clip one out of the other it clips all the overlapping buffers (which is what I expected) but I can't seem to figure out how to get the result I would like. I feel like I need to split each of the the buffer datasets so that it does the clip on each pair of polygons separately but - I'm new-ish to FME so.... Can't seem to find anything to help online either.

 

This is what I have - the attribute managers are just to fill in an attribute so I can put the two buffers back together in one layer and be able to identify which polygon is which type.

imageThis is what I would like to end up with:

imageNot this:

image

icon

Best answer by tomfriedl 31 March 2023, 07:51

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6 replies

tomfriedl
Rank
Userlevel 2
Badge +12

Have you activate "Group Procesing" in the clipper params?

https://community.safe.com/general-10/fme-form-starter-20721
dustin
Rank
Userlevel 3
Badge +26

Agreed on the Group By Processing in the Clipper being the key. If you don't have a unique attribute on the features, you can create it in your AttributeManager.

M
Badge +2

@hoskinmi​ or try AreaOnAreaOverlayer instead of Clipper

H

Have you activate "Group Procesing" in the clipper params?

Thanks so much - that did it - and super easy too! How did I not see this? :)

H

Agreed on the Group By Processing in the Clipper being the key. If you don't have a unique attribute on the features, you can create it in your AttributeManager.

Thanks for helping - this was the solution and I do have a unique id already so it was very easy.

H

@hoskinmi​ or try AreaOnAreaOverlayer instead of Clipper

I didn't try this as the Group Processing on the clipper did it but thanks so much for helping. I'll get my head around the AreaOnAreaOverlayer at some point I'm sure.

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