Luke W Rogers
lwrogers at u.washington.edu
Wed Sep 12 14:18:43 PDT 2001
And you have updated the Area attribute using the Calculate Area, Perimeter,
Length tool in XTools?
From: UW-GIS-L-owner at u.washington.edu
[mailto:UW-GIS-L-owner at u.washington.edu]On Behalf Of R. Morse
Sent: Wednesday, September 12, 2001 2:13 PM
To: UW - GIS Discussion & Support
Subject: Multipart Polygons
I've been trying to determine why two shapefiles, that are each the result
of multiple overlays, don't have the same total area, as they should.
Both have been clipped with the same polygon so there is no overlap or
shortfall at the edge of the layers. My guess is that multipart polygons
in early layers created overlapping polygons when the final layers were
produced, and these overlapping polygons are causing some area to be
double counted. Are there ways to locate these areas of overlap in the
latter product and to identify multipart polygons before the overlay
process? One thought has been to generate a centroid for each polygon with
the hope of locating overlaps where identical centroids coexisted, but
have had no luck with that yet.
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