> Rather tricky. The same analysis seems to run fine, however, on the same > data with different software.
On individual polygons yes. But if you just aggregate all the polygons as a multipolygon (what gdalwarp does), it becomes invalid. > What would be your advice for gdalwarp usage in QGIS>Processing? Just > adding GDALWARP_IGNORE_BAD_CUTLINE YES by default, and perhaps an extra > option to disable it? Possibly. I've just fixed the issue per https://trac.osgeo.org/gdal/ticket/6694 and will issue a GDAL 2.1.2 RC4 with that extra fix. > > > Probably that in the use case you point, the way the multipolygon is > > built should be revised to use a proper unioning operation instead of > > the current rather naive way. Could be worth a ticket. > > > > You can do that step manually with: > > > > ogr2ogr cutline.shp -sql "select st_union(geometry) from watersheds" > > watersheds.shp -dialect sqlite > > Unfortunately this removes all internal borders, making it unusable for > the original purpose. Hum, I'm not sure to understand. I don't see any difference when running gdalwarp with your cutline (with --config GDALWARP_IGNORE_BAD_CUTLINE YES or after my fix) or the cutline resulting of the union (anyway my fix doesn't involve union'ing). Or perhaps if you enable blending ? Even -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
