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Alteryx Designer Desktop Discussions

Find answers, ask questions, and share expertise about Alteryx Designer Desktop and Intelligence Suite.

Polygon and spatial match, bug ?

_olivierbisthoven
7 - Meteor

Hi Community,

 

As nobody have found explanations to the following problems, I reintroduce it with a bug label

 

I try to match the content of two shapefiles using the predicate Target Within Univers and I observe unexpected behavior.

 

The two files in the samples contains one polygon each. obj1.shp is included in obj2.shp : A quick check with Brower tool show that is correct.

Nevertheless using Spatial Match on this very simple example fails !

 

On the other side using Custom DE-9IM spec coding "within" i.e.  T*F**F*** the result is correct !

 

Could anyone explains this strange result

 

 

6 REPLIES 6
GiuseppeC
Alteryx
Alteryx

Hi @_olivierbisthoven,

 

the only explanation is that the 'small' polygon defined in obj1.shp contains something else that is not visible on the map.

 

If you see my attachment, I used the Summarize tool to Combine the 2 polygons. Then used the SpatialInfo tool to get the areas and compared obj2's area to the area of the 'combined' polygon (i.e. obj1+obj2). They are different in size (obj2: 8.63762439090817e-04 vs combined: 8.64073468040519e-04 SqKm) and the fact that the matching with the "within" setting is not happening, tells me that obj1 contains something that's outside of obj2.

The SpatialMatch would find a match if you switched the setting to 'intersects'.

 

Hope this helps!

 

Giuseppe

danilang
19 - Altair
19 - Altair

Hi @GiuseppeC 

 

I thought it might have been something like that so I split the polygons to points to see if there might be an outlier.  

 

split.png

 

Each poly is made up of only 4 points and the target, last 5 rows (because of the closure), is definitely contained within the area of the universe.

 

Dan

_olivierbisthoven
7 - Meteor

Hi Dan,

 

Correct !

I have also split obj1 polygon in points and the all the points are contained in obj2

 

The question is still open ...

 

Thanks

Hollingsworth
12 - Quasar
12 - Quasar

Very weird. I did all of my standard tricks to investigate and this makes no sense to me.

John Hollingsworth
Clear Channel Outdoor
Jacob_Yurek
5 - Atom

I am encountering this same problem, wondering if anyone managed to fix it @GiuseppeC @danilang @_olivierbisthoven 

GiuseppeC
Alteryx
Alteryx

@Jacob_Yurek, I was able to replicate this issue again. I have opened a case on the internal Community. Will let you know when I hear back.

 

Thanks,

Giuseppe

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