|Version 10 (modified by 11 years ago) ( diff ),|
For portability, the default storage for Features is the normal database via Web2Py's DAL.
In order to support Lines & Polygons we need to store as WKT
We can extend DAL for spatial support:
- adding if deployment_settings.gis.spatialdb == True and deployment_settings.database.db_type == "postgres" to routines inside S3GIS' spaital functions to use optimsied routines where possible & falling back to the existing Shapely routines.
Since we store features in Lat/Lon then we need to use the geography_columns, which stay updated automatically :)
geog GEOGRAPHY(Point) geog GEOGRAPHY(Polygon) ST_Distance(geography, geography) returns double ST_DWithin(geography, geography, float8) returns boolean ST_Area(geography) returns double ST_Length(geography) returns double ST_Covers(geography, geography) returns boolean ST_CoveredBy(geography, geography) returns boolean ST_Intersects(geography, geography) returns boolean ST_Centroid(geometry) returns a point that is approximately on the center of mass of the input argument. This simple calculation is very fast, but sometimes not desirable, because the returned point is not necessarily in the feature itself. If the input feature has a convexity (imagine the letter ‘C’) the returned centroid might not be in the interior of the feature. ST_PointOnSurface(geometry) returns a point that is guaranteed to be inside the input argument. It is substantially more computationally expensive than the centroid operation
Q: integrate FeatureServer?
Q: use GeoAlchemy?
Q: copy GeoDjango?