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Identify non exact overlapping polygons?

  • July 13, 2017
  • 6 replies
  • 158 views
C
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Hi,

I am currently working on a project where I am trying to identify non exact overlapping polygons. For example the polygons in the first image below would be highlighted as they overlap but not exactly. In the second image the polygons would be ignored as they are an exact overlap of each other:

I tried using the matcher to remove the exact copies followed by the spatialrelator but this seemed to return polygons which don't overlap or intersect with any other polygons.

If anyone could provide any advice on the best way of doing this that would be great. If there is any further information I can provide please let me know.

Thanks for your help.

Thanks,

Charlie

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6 replies

redgeographics
Celebrity
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I did the Matcher and SpatialRelator approach as well, but supplied a unique id attribute for each feature and specified in the SpatialRelator that that had to differ. This prevents a feature to check for any spatial relationship with itself.

The predicates I tested for were CONTAINS, TOUCHES and WITHIN, but not EQUALS (though that shouldn't happen anyway, that's what the Matcher is for)

FME rocks! \m/
takashi
Celebrity
  • takashiCelebrity
  • July 13, 2017

I think the SpatialRelator with the "Overlaps" predicate does the trick. Send all the polygons to both Requestor and Supplier ports simultaneously.

See here to learn more about Spatial Predicates: Spatial Relations Defined

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
thomas_g
Contributor
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  • thomas_gContributor
  • Contributor
  • July 13, 2017

Hi,

I used an AreaOnAreaOverlayer first, and used the new created polygons ( _overlaps > 1 ) as filter for the SpatialFilter where I used "Filter is within Candidate".

ebygomm
Influencer
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  • ebygommInfluencer
  • Influencer
  • July 13, 2017

I think the SpatialRelator with the "Overlaps" predicate does the trick. Send all the polygons to both Requestor and Supplier ports simultaneously.

See here to learn more about Spatial Predicates: Spatial Relations Defined

This won't report this sort of overlap, which may or may not be important

 

takashi
Celebrity
  • takashiCelebrity
  • July 13, 2017

This won't report this sort of overlap, which may or may not be important

 

According to the definitions of spatial predicates, this is "Contains" or "Within", and is not "Overlaps". If you need to detect "Contains" and "Within" (but not "Equals") too, the workflow has to be modified of course.

 

Why not inspect features with Visual/Data Preview and Feature/Record Information before writing them into a destination dataset?
ebygomm
Influencer
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  • ebygommInfluencer
  • Influencer
  • July 13, 2017
According to the definitions of spatial predicates, this is "Contains" or "Within", and is not "Overlaps". If you need to detect "Contains" and "Within" (but not "Equals") too, the workflow has to be modified of course.

 

Agree it's not an overlap according to spatial predicates but in day to day language this is often referred to as an overlap in my experience

 

 

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