Question

Create depth zones (polygons) from depth contours (polylines)

  • 27 August 2018
  • 2 replies
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aron
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  • aron Contributor
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I am trying to create depth zones (polygons) from a set of depth curves (polylines). I would like to create one polygon that covers the area between the 0m and 3m curves, one that covers the area between 3m and 6m, and so on. There are also shallows and deeps that need to be taken into consideration. What would be the best practise to do this?

I have experimented with Testfilter » Areabuilder » Disolver » Clipper. But that quickly gets very convoluted...

I am guessing that I could use one of the donut transformers to manage the shallows and deeps?

2 replies

takashi
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Badge +17

Hi @aron, if every contour line was a closed line (i.e. the end node is equal to the start node), just send all the lines into an AreaBuilder (Drop Holes: No). I think the resulting areas would be your desired shapes.

aron
Rank
Badge +14

Hi @aron, if every contour line was a closed line (i.e. the end node is equal to the start node), just send all the lines into an AreaBuilder (Drop Holes: No). I think the resulting areas would be your desired shapes.

Yes, that was a simpler solution than my own convoluted attempts :)

 

 

I am still running into one issue though. There are islands in the lakes, so sometimes the lake is on the inside of the contour, and sometimes on the outside. The depth zones need to be constructed accordingly. Is there some way to change the "direction" of a line? So that FME works towards the outside in stead of the inside?

 

 

The picture below is from the same lake as earlier, blue is water, white is land. Note all the islands.

 

 

 

 

skapa-djupzoner-v2-terrangdata.fmw

 

 

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