Le mercredi 07 mai 2014 20:30:45, scottm361 a écrit : > I am a developer on an application that will potentially use ogr2ogr to > re-project shapefiles (and potentially other ogr supported formats) > > What I am wondering about is the nature of geometry error handling in > ogr2ogr. My assumption is that geometry errors are quite common in user > supplied data, so I am wondering if I need to rethink the automated use of > ogr2ogr for this purpose. > > Geometry errors that I have encountered so far are: > > ERROR 1: TopologyException: found non-noded intersection between LINESTRING > (-1.77558e+006 7.46242e+006, -1.77596e+006 7.46259e+006) and LINESTRING > (-1.77596e+006 7.46259e+006, -1.77593e+006 7.46258e+006) at > -1775935.412652828 7462582.2040281445 > > ERROR 1: TopologyException: side location conflict at -1828580.797204141 > 7355153.6866245456 > > ERROR 1: TopologyException: unable to assign hole to a shell >
Those are GEOS errors. Are you doing some clipping/spatial filtering too ? What is your ogr2ogr command line ? > > My questions: > > 1. Does ogr2ogr omit the offending geometries above (or others) when > -skipfailiures is used in the resulting output It is difficult to tell for sure. It might depend on the call site that triggers the error > 2. Are geometry errors ever "created" by reprojection? Presumably due to > floating point error some geometries might be shifted slightly relative to > each other. Reprojection could create topological weirdness. For example if you convert a polygon from polar projection to geodetic projection. > 3. If the answer to 2 is "Yes", does that mean topology exceptions like > above are thrown when detected in the source data, AND in the process of > reprojecting the result? > 4. Generally speaking, from a reliablility and data integrity standpoint, > are errors such as these safe to ignore and carry on processes using > -skipfailiures, or will users be dismayed by things such as missing > features, which are indirectly a result of their own bad data > 5. Is there any way to fix the geometry in the OGR context before > attempting to reproject? > > Thank you ! > Scott Morken > > > > > -- > View this message in context: > http://osgeo-org.1560.x6.nabble.com/ogr2ogr-error-handling-tp5139067.html > Sent from the GDAL - Dev mailing list archive at Nabble.com. > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev -- Geospatial professional services http://even.rouault.free.fr/services.html _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
