PostGIS
Spatial and Geographic objects for PostgreSQL
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Upcoming events of interest.
PostgreSQL Sessions (Paris)Tips
Getting intersections the faster way
Doing an ST_Intersection is much slower than relation checks such as
ST_Intersects
, ST_CoveredBy, and , ST_Within .
In many situations you know the intersection of 2 geometries
without actually computing an intersection. In these cases, you can skip the costly ST_Intersection call. Cases like this:
- geometry a is covered by geometry b -> intersection is geometry a
- geometry b is covered by geometry a -> intersection is geometry b
- geometry a does not intersect geometry b -> intersection is empty geometry
This kind of question comes up a lot: As discussed in stackexchange Acquiring ArcGIS speed in PostGIS
Case Studies
Institut Géographique National
The Institut Géographique National (IGN) is the national mapping agency for France, with 1800 employees and a mandate to collect, integrate, manage and distribute reference geographical information for the whole country.
InfoTerra
Infoterra has been in the geospatial business for over 25 years, since its founding in 1980 as the UK National Remote Sensing Centre. In that time, NRSC grew, formed international partnerships with space agencies, expanded into aerial data collection, and was eventually privatized and re-named “Infoterra” in the late 1990s.