Shapefile import deficiencies (patch)
|Reported by:||tms13||Owned by:||cbro@…|
The current implementation of shapefile reading has the following issues:
- Coincident nodes are not shared between features
- Polygons with holes are not converted to multipolygon relations
- Projection is done one node at a time, rather than a geometry at a time (x2 performance hit(*))
(*) I'm guessing that the GDAL library can use SIMD instructions when doing bulk transforms, which might explain this.
My patch is tested and ready to apply.
Note that the Ordnance Survey "VectorMap? District" NaturalFeature_Area.shp tiles have lots of 'Custom Landform' polygons with holes, so performance can be improved by generating a more specific file using ogr2ogr to crop or select features. It may be an idea to somehow allow the user to specifiy what feature types should be imported...