Hi all, First post but have been lurking for a long time.
In the process of migrating some geoprocessing procedures over to our open
source stack, I came across a difference in results from postgis' st_union vs.
arcgis' dissolve. From what I can tell these functions should be synonymous in
theory, despite their naming. (?)
It seems like st_union is not doing a "clean" union, some slivers are
remaining.
Original parcel fabric: http://quimby.ca/original.jpg
Dissolved by ArcGIS: http://quimby.ca/dissolved_by_arcgis.jpg
st_union by postgis: http://quimby.ca/dissolved_by_postgis.jpg
The input to both functions was the same table in postgis. I am defining the
geometry simply as select st_union(current_assessment_parcel.the_geom) AS
the_geom
Postgresql 8.4.1
Postgis 1.4
Is this simply a difference in tolerance? or am I seeing something else here.
Thanks,
Lee.
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