Not make sense, the function exists since v2.2,
SELECT distinct geometrytype(geom) from t; -- POLYGON
SELECT ST_ApproximateMedialAxis(geom) from t;
-- ERROR: function st_approximatemedialaxis(geometry) does not exist
-- LINE 1: select ST_ApproximateMedialAxis(geom) from t...
select PostGIS_Version()= "3.0 USE_GEOS=1 USE_PROJ=1 USE_STATS=1"select select postgis_full_version()= POSTGIS="3.0.1 ec2a9aa" [EXTENSION] PGSQL="120" GEOS="3.8.0-CAPI-1.13.1 " PROJ="6.3.1" LIBXML="2.9.10" LIBJSON="0.13.1" LIBPROTOBUF="1.3.3" WAGYU="0.4.3 (Internal)select Version()= "PostgreSQL 12.3 (Ubuntu 12.3-1.pgdg20.04+1) ... 64-bit"\df st_area, and all other are there...\df public.ST_ApproximateMedialAxis= no function!
This last check shows that was not installed (!)... Well, the guide say "This method needs SFCGAL backend", how to check it?
1 Answer
Seems so simple
CREATE EXTENSION postgis_sfcgal;
\df public.ST_ApproximateMedialAxis
List of functions
Schema | Name | Result data type | Argument data types | Type
--------+--------------------------+------------------+---------------------+------
public | st_approximatemedialaxis | geometry | geometry | func
Thanks to @JGH and
Now postgis_full_version() shows also SFCGAL version, SFCGAL="1.3.7".
