gbuilder

Extension for PostgreSQL that adds various geometry builders. Only supports the creation of a concave hull at the moment. The extension is compiled against liblwgeom, so that it can use the PostGIS geometry types directly.

Dependencies

• PostgreSQL >= 9.6
• PostGIS >= 2.5
• Fast Robust Predicates

Installation

Build and install the extension:

make
sudo make install

And enable it in PostgreSQL:

CREATE EXTENSION postgis;
CREATE EXTENSION gbuilder;

ConcaveHull

Construct a concave hull from a set of points. There is also a non-aggregate function available that accepts a custom alpha value. It is useful to note that this concave hull algorithm is vastly superior to the internal PostGIS version in both speed and precision.

SELECT ConcaveHull(geom)
FROM planet_osm_point p
WHERE p."public_transport" = 'stop_position'
AND p.geom && ST_Buffer(ST_GeomFromText('POINT(4.48187 51.94380)', 4326), 0.05);