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Invert polygons

  • April 14, 2017
  • 2 replies
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B

I have the sea as polygons in an esri shapefile. But now I need to invert this - I need to make polygons of everything that is not sea. How do I do this? I have tried searching for FME help on "inverting polygons" and other related, but no luck, there must be such an transformer though... :) ?

Thanks,

Ben

Best answer by takashi

Hi @benjamin, if you need to get continents and islands surrounded by the sea, send the sea polygon to a DonutHoleExtractor. Then, the land areas will be output via the Hole port.

If you need to get an outer donut area surrounding the sea, create an enough large area that contains the sea, then send the large area and the original sea to a DonutBuilder (Drop Holes: Yes) together.

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2 replies

itay
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  • itaySupporter
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  • April 14, 2017

I would filter out the sea and use the AreaBuilder to create polygons from the rest.

takashi
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  • takashiCelebrity
  • Best Answer
  • April 14, 2017

Hi @benjamin, if you need to get continents and islands surrounded by the sea, send the sea polygon to a DonutHoleExtractor. Then, the land areas will be output via the Hole port.

If you need to get an outer donut area surrounding the sea, create an enough large area that contains the sea, then send the large area and the original sea to a DonutBuilder (Drop Holes: Yes) together.

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?

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