CG_3DUnion
Indietro  8.3. SFCGAL Processing and Relationship Functions  Avanti

Nome

CG_3DUnion — Perform 3D union using postgis_sfcgal.

Sinossi

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

Union two overlapping tetrahedral solids.

Code
WITH solids AS (
  SELECT CG_MakeSolid('POLYHEDRALSURFACE Z (
           ((0 0 0,4 0 0,0 4 0,0 0 0)),
           ((0 0 0,0 0 4,4 0 0,0 0 0)),
           ((0 0 0,0 4 0,0 0 4,0 0 0)),
           ((4 0 0,0 0 4,0 4 0,4 0 0)))'::geometry) AS geom1,
         CG_MakeSolid('POLYHEDRALSURFACE Z (
           ((2 0 0,6 0 0,2 4 0,2 0 0)),
           ((2 0 0,2 0 4,6 0 0,2 0 0)),
           ((2 0 0,2 4 0,2 0 4,2 0 0)),
           ((6 0 0,2 0 4,2 4 0,6 0 0)))'::geometry) AS geom2
)
SELECT CG_3DUnion(geom1, geom2) AS union_result
FROM solids;
Output
POLYHEDRALSURFACE Z (((2 0 0,0 0 0,2 2 0,2 0 0)),((2 0 2,0 0 0,2 0 0,2 0 2)),((0 0 4,0 4 0,0 0 0,0 0 4)),((2 0 2,0 4 0,0 0 4,2 0 2)),((0 4 0,2 2 0,0 0 0,0 4 0)),((2 2 0,0 4 0,2 0 2,2 2 0)),((0 0 0,2 0 2,0 0 4,0 0 0)),((4 0 0,2 0 0,2 2 0,4 0 0)),((4 0 0,2 0 2,2 0 0,4 0 0)),((4 0 0,2 2 0,6 0 0,4 0 0)),((2 0 2,4 0 0,2 0 4,2 0 2)),((2 0 2,2 4 0,2 2 0,2 0 2)),((2 4 0,2 0 4,6 0 0,2 4 0)),((2 2 0,2 4 0,6 0 0,2 2 0)),((2 4 0,2 0 2,2 0 4,2 4 0)),((4 0 0,6 0 0,2 0 4,4 0 0)))
Figure
Geometry figure for visual-cg-3dunion-01