Name
CG_3DUnion — Perform 3D union using postgis_sfcgal.
Synopsis
geometry CG_3DUnion(geometry geom1, geometry geom2);
geometry CG_3DUnion(geometry set g1field);
Descrizione
Availability: 3.5.0
Questo metodo richiede il backend SFCGAL.
Questo metodo implementa la specifica SQL/MM. SQL-MM IEC 13249-3: 5.1
Questa funzione supporta il 3d e non distrugge gli z-index.
Questa funzione supporta le Polyhedral Surface.
Questa funzione supporta i Triangoli e le Triangulated Irregular Network Surfaces (TIN).
Aggregate variant: returns a geometry that is the 3D union of a rowset of geometries. The CG_3DUnion() function is an "aggregate" function in the terminology of PostgreSQL. That means that it operates on rows of data, in the same way the SUM() and AVG() functions do and like most aggregates, it also ignores NULL geometries.
Esempi
3D images were generated using PostGIS ST_AsX3D and rendering in HTML using X3Dom HTML Javascript rendering library.
SELECT CG_Extrude(ST_Buffer(ST_GeomFromText('POINT(100 90)'),
50, 'quad_segs=2'),0,0,30) AS geom1,
CG_Extrude(ST_Buffer(ST_GeomFromText('POINT(80 80)'),
50, 'quad_segs=1'),0,0,30) AS geom2;
 Original 3D geometries overlaid. geom2 is the one with transparency. |
SELECT CG_3DUnion(geom1,geom2)
FROM ( SELECT CG_Extrude(ST_Buffer(ST_GeomFromText('POINT(100 90)'),
50, 'quad_segs=2'),0,0,30) AS geom1,
CG_Extrude(ST_Buffer(ST_GeomFromText('POINT(80 80)'),
50, 'quad_segs=1'),0,0,30) AS geom2 ) As t;
 Union of geom1 and geom2 |