Skip to main content
Question

Identify non exact overlapping polygons?

C
Forum|alt.badge.img

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

6 replies

redgeographics
Celebrity
Forum|alt.badge.img+49

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)

takashi
Influencer
  • takashiInfluencer
  • 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

thomas_g
Contributor
Forum|alt.badge.img+8
  • 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
Forum|alt.badge.img+33
  • ebygommInfluencer
  • Influencer
  • July 13, 2017
takashi wrote:

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
Influencer
  • takashiInfluencer
  • July 13, 2017
ebygomm wrote:

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.

 

ebygomm
Influencer
Forum|alt.badge.img+33
  • ebygommInfluencer
  • Influencer
  • July 13, 2017
takashi wrote:
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

 

 

Reply


Helpful Members This Week

Community Stats

31,182
Posts
118,184
Replies
38,791
Members

Latest FME

Terms & ConditionsCookie settings

Cookie policy

We use cookies to enhance and personalize your experience. If you accept you agree to our full cookie policy. Learn more about our cookies.

 
Cookie settings
A product of
Safe Software respectfully acknowledges that we live, learn and work on the traditional and unceded territories of the Kwantlen, Katzie, and Semiahmoo First Nations.