I've spent some days enhancing the XMLTester to check for validity of returned geometries and found a dozen or more such cases (6 couple of inputs, multi-ops for some of them).
All the invalidities come out from GEOS unchecked use of CommonBitsOp, whereas such operation is known to possibly yeld collapsed poligons due to loss of precision when translating back (re-adding the previously stripped bits). In JTS, an EnhancedBitsOp class is used to basically add a validity check around the CommonBitsOp to ensure the result would be checked before returning. In GEOS, doing a similar thing would be nice as we could then try something else (SnapOp). Well, I did and that fixed 5 over 6 tests. Unfortunately the last test broke completely, that is it would not return an invalid geometry (as it did before) but rather an exception. OUT OF DETAIL, INTO THE POINT Ok, simple question for you now is: Should GEOS always throw an exception in preference over returning an invalid geometry ? --strk; () Free GIS & Flash consultant/developer /\ http://strk.keybit.net/services.html _______________________________________________ geos-devel mailing list geos-devel@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/geos-devel