[Gvsig_english] Geoprocessing: Difference-Tool

[Benjamin Ducke]

One of your input polygons seems to have a digitization
error, resulting in bad topology. While it is normally
possible to display geometries with faulty topologies,
processing them is not.

Your best option is to validate the input layer with the
tools in the Topology Extension, locate the defective polygon 
and repair it.

Ben

----- Ursprüngliche Mail -----
> Dear gvSIG Community,
> I have problems using the difference option of the geoprocessing
> manager (overlay).
> Normally it works very good.
> But I have one polygon-theme (see attachment ausschnitt.shp), which
> doesn't works.
> I got the message below.
> Is there a limitation for the number of elements in this shape?
> Do you have an idea, what I can do?
> Thanks a lot
> Rolf
> 
> 
> 
> ********************** ERROR MESSAGE ******************************
> null com.vividsolutions.jts.geom.TopologyException: found non-noded
> intersection between LINESTRING ( 236.80441645812243
> 356.21349653881043, 236.529304722324 349.8171486798674 ) and
> LINESTRING ( 236.80441645439714
> 356.14471860881895, 236.04785918071866 356.14471860881895 ) [
> (236.80145826758593, 356.14471860881895, NaN) ]
> com.vividsolutions.jts.noding.FastNodingValidator.checkValid(FastNodingValidator.java:109)
> com.vividsolutions.jts.geomgraph.EdgeNodingValidator.checkValid(EdgeNodingValidator.java:94)
> com.vividsolutions.jts.geomgraph.EdgeNodingValidator.checkValid(EdgeNodingValidator.java:59)
> com.vividsolutions.jts.operation.overlay.OverlayOp.computeOverlay(OverlayOp.java:170)
> com.vividsolutions.jts.operation.overlay.OverlayOp.getResultGeometry(OverlayOp.java:127)
> com.vividsolutions.jts.operation.overlay.OverlayOp.overlayOp(OverlayOp.java:66)
> com.vividsolutions.jts.operation.overlay.snap.SnapOverlayOp.getResultGeometry(SnapOverlayOp.java:68)
> com.vividsolutions.jts.operation.overlay.snap.SnapOverlayOp.overlayOp(SnapOverlayOp.java:25)
> com.vividsolutions.jts.operation.overlay.snap.SnapIfNeededOverlayOp.getResultGeometry(SnapIfNeededOverlayOp.java:76)
> com.vividsolutions.jts.operation.overlay.snap.SnapIfNeededOverlayOp.overlayOp(SnapIfNeededOverlayOp.java:25)
> com.vividsolutions.jts.geom.Geometry.difference(Geometry.java:1163)
> com.vividsolutions.jts.precision.EnhancedPrecisionOp.difference(EnhancedPrecisionOp.java:127)
> ........
> 
> --
> _________________________________________________ Rolf Annecke
> Referat für Gesundheit und Umwelt
> Abteilung Umweltschutz
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> 80335 München
> 
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> 
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> 
> 
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