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PointOnPointOverlayer - Attribute Accumulation ?

  • 29 November 2016
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lifalin2016
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Hi,

I'm using PointOnPointOverlayer to match a set of anonymous points to a set of named points, wanting to transfer the "point name" of the latter to the former when they have identical coordinates.

However, I'm curious about the "Attribute Accumulation" setting, which doesn't make much sense to me.

Both sets of points are routed into the transformer via a single port, but the transformer nonetheless talks about "Original" and "Incoming" as if there is a requestor port and a supplier port (as in multiple other transformers).

I assume that the PointOnPointOverlayer makes a "full join" between all point features. Is this so ?

What should I expect from "Use Original" vs "Use Incoming" when I've chosen "Merge Incoming" as my mode ?

Cheers

Lars I.

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Best answer by redgeographics 29 November 2016, 14:12

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-- Cheers, Lars I.

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lifalin2016
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2016-11-29-13-07-32-vm-fme-forbindelse-til-fjernsk.png

 

Screendump of the transformer setting.

 

Using 2016.1

 

-- Cheers, Lars I.
lifalin2016
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The same issue is with PointOnLineOverlayer, with the twist of having two inputs named "Point" and "Line", but an Attribute Accumulation that instead talks about "Original" and "Incoming".

 

 

From a little testing it seems that Point = Original and Line = Incoming (which btw is contrary to my expectation, as the transformer cuts lines), but the nomenclature makes little sense in any case.

 

-- Cheers, Lars I.
redgeographics
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It seems that (probably per matching pair/group) the first feature coming in is deemed to be the "original" and all subsequent ones are "incoming". You can control the order of the readers in your workspace to influence this but if you do a lot of pre-processing before the overlay the order of the features may be affected.

A potential workaround in case you want more control:

If you grab the geometry of the points (maybe do an AnchoredSnapper first to make sure they match) and use that as a matching attribute in a FeatureMerger you have more control over what comes in and what goes out.

Hope this helps.

 

lifalin2016
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Userlevel 1
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Ok, I reread the docs for PointOnLineOverlayer. I was focused solely on the "Line" output, although it also has a "Point" output. "Original" is of course points when Point, and lines when Line.

 

-- Cheers, Lars I.

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