ST_ApproximateMedialAxis(geometry) does not exist?

user_287948 0
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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?

postgis
1 Answers

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 https://gis.stackexchange.com/a/179618/7505

Now postgis_full_version() shows also SFCGAL version, SFCGAL="1.3.7".

user_2879480
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