In QGIS, I'm using Difference (under the Geoprocessing menu) to subtract a complicated shapefile with plenty of features from another complicated shapefile.
For 90% of the features, it works correctly. But for some, it ends up deleting the underlying feature altogether, instead of returning the difference -- even though the "Difference" feature didn't entirely cover up the underlying feature.
Here's an example:
The selected feature on the base layer.
The soon-to-be-Difference layer, in pink. Note that the selected feature is not wholly obscured by the difference layer, so it should show up in the final result.
The resulting shapefile. Note that the previously selected area is entirely blank (along with a good deal of the map that shouldn't be, as well.)
أكثر...
For 90% of the features, it works correctly. But for some, it ends up deleting the underlying feature altogether, instead of returning the difference -- even though the "Difference" feature didn't entirely cover up the underlying feature.
Here's an example:
The selected feature on the base layer.
The soon-to-be-Difference layer, in pink. Note that the selected feature is not wholly obscured by the difference layer, so it should show up in the final result.
The resulting shapefile. Note that the previously selected area is entirely blank (along with a good deal of the map that shouldn't be, as well.)
أكثر...