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Question

Find the "corners" of irregular polygons?


aron
Supporter
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The polygons below have corners that are 90 roughly degrees. I would like to split them at the corners so that I get four lines from each polygon for further processing.

The two areas below are only examples, but the rest of the data have similar elongated, bent shapes. 

I tried finding the corners by intersecting against a bounding box but the result was not very useful because of the irregularity of the shapes. 

My guess is that I would get the best result by measuring where the vertex take a 80-100 degree turn. Any suggestions on how to achieve this? Or other clever ways to breake the polygons appart?

 

4 replies

david_r
Evangelist
  • October 7, 2024

Maybe this FME Hub transformer from Vicrea can help:

https://hub.safe.com/publishers/vicrea/transformers/vertexanglecalculator


geomancer
Evangelist
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  • Evangelist
  • October 7, 2024

Have you tried the rotated boundingbox? Maybe you can identify the corner points of your feature that are nearest to the vertices of the rotated bounding box?

Or maybe you can use the PolylineAnalyzer from FME Hub (also works on polygons) to identify the corners that are roughly 90 degrees - Or take a look at the HorizontalAngleCalculator from FME Hub.


nielsgerrits
VIP
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david_r wrote:

Maybe this FME Hub transformer from Vicrea can help:

https://hub.safe.com/publishers/vicrea/transformers/vertexanglecalculator

This one is password protected, I never dare to run a custom transformer from the hub without checking the internals. I’ve been Rick rolled before ;)


aron
Supporter
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  • Author
  • Supporter
  • October 8, 2024

The  PolylineAnalyzer from FME Hub did a fine job identifying the corners. Thanks all!


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