Question

Clipping and simplifying AGOL polygons

  • 17 February 2023
  • 3 replies
  • 2 views
A

Hi all,

 

I have an "issue" that is frustrating me to no end (probably because the answer is more simple than I'm making it), so I thought I'd run it by the community.

 

I have a workbench where I am taking AGOL features and converting them to a dwg. The AGOL geometry that is giving me issues are the AGOL polygons after they are sent through a CLIPPER:

 

image 

I understand why the 'RESULT' is passed through the CLIPPER and spit out as polygons still. And I have them also going through a GEOMETRY COERCER (to fme_line) and even a LINE ON LINE OVERLAYER -- all good to this point.

 

What I cannot figure out is how to remove the unwanted lines to obtain the "DESIRED RESULT", which would just be lines once they get into AutoCAD. There doesn't seem to be an attribute that I can use to differentiate whether the line came from the original polygon or if it is a result of the CLIPPER 'changing' the geometry (all geometry has the attribute "_clipped" as "yes").

 

These are similar to quarter sections, so obviously I would prefer not to have the clipped areas show up as closed in AutoCAD and give the user misleading boundaries.

 

Hoping someone can make me feel stupid because I've been staring at this for longer than I'd like.

 

Thank you!

3 replies

A

I thought of trying to process the 'quarter section' polygons prior to them going through the clipper, but I worry about the performance hit the end-user will take when doing one of these exports as it will process all of the polygons in the city rather than just the ones in the area specified.

A

Another strange thing is that the center square also gets a clipped=yes attribute even though I believe it should =no because the clipper boundary isn't touching it.

 

hkingsbury
Rank
Userlevel 5
Badge +29

Your inputs are polygons, therefore the outputs of the clipper are polygons. In your third picture, you either have:

  1. four intersecting lines
  2. the same four lines with a polygon in the middle
  3. a polygon with two lines (8 in total) coming off of each corner
  4. 12 lines in total, each starting/ending where they cross

 

I've attached an example showing how you'd achieve #4 (as its probably the most straight forward).

 

 

Check out the Abley FME Firesides on Youtube: https://www.youtube.com/@ableyltd

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