[postgis-devel] strange problem with operators

[David Blasby]

By converting from geometry->text->geometry you're probably moving
around your vertices "just a little bit" (ie. < 10^-8).

The new location of the vertices gives a geometry that interacts
"better" and doesnt throw the error.

At least that what it looks like,

dave

On Tue, 10 Aug 2004 13:58:29 -0400, Carl Anderson
<carl.anderson at co.fulton.ga.us> wrote:
> Working with postgresql-7.4.3 and  GEOS (cvs) and PostGIS (cvs)
> 
> I have found a condition where
> 
> select difference (geometry(shp1),geometry(shp2)) from zoning_test.bad;
> NOTICE:  TopologyException: no outgoing dirEdge found
> (2.23561e+06,1.42152e+06)
> ERROR:  GEOS difference() threw an error!
> 
> BUT
> 
> select difference (geometry(astext(shp1)),geometry(astext(shp2))) from
> zoning_test.bad;
> 
> succeeds
> 
> Any hints as how to extract the geometries for analysis
> 
> I got there by
> 
> shp1 = difference (shp1,shp0)
> then
> shp2 = difference( shp1,shp2)    -- fails
> 
> BTW
> PostGIS (cvs) depends on Proj 4.4.8  (pj_get_release)
> Can a note be added to the Makefile or CHANGES
> 
> C.
> 
> --
> Carl Anderson
> GIS Manager Fulton County, Georgia
> carl.anderson at co.fulton.ga.us
> 404.730.8026
> 
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