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| GeoCommunity Mailing List |
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| Mailing List Archives |
| Subject: | Re: [gislist] Align/Match layers from same area |
| Date: |
04/09/2004 07:45:00 PM |
| From: |
Paul Ramsey |
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Your problem is entirely automatable, the JCS plugin for road matching
does quite similar things. Here is a question though -- if the polygons
are so similar, why bother to do matching at all? Choose a reference
layer (the one you like the spatial qualities of) then turn the other
layer into centroid points and do simple point-in-polygon processing to
transfer the attributes to the reference layer.
The trouble with conflation is that the best processes use knowledge of
the input data in order to make the best matches, and each matching
problem has its own set of inputs, and own desired decision process for
doing matches. Knowing the playing field allows one to write really
good code to automate a maximum quantity of the problem. But a priori
knowledge of the problem mitigates against being able to provide COTS
solutions to conflation problems. COTS solutions end up being "better
than nothing" but a long shot worse than the best automated process
that is possible.
Paul
On Friday, April 9, 2004, at 11:10 AM, Mach Chnife wrote:
> Hi Group,
>
> I need to align/match two parcels layers of the same
> area but from different sources. Is there a sofware or
> a script/plug-in/add-on to do this?
>
> Here is some more details:
>
> Most of the polygons on the two layers are the same.
> They just have a slight irregular offset between them
> (<0.25 m). So It would be nice if the new layer (A)
> could be snapped to the more accurate base layer (B)
> we already have in our system.
>
> The problem is, intersections of A must snap to
> corresponding intersections of B: segments of A must
> snap to corresponding segments of B. Sometimes, for
> corresponding segments, A has two vertices but B has
> three (example). Than a vertex must be added to A for
> a proper alignment.
>
> Is there any way to do this almost automatically?
>
Paul Ramsey
Refractions Research
Email: pramsey@refractions.net
Phone: (250) 885-0632
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