Name
ST_3DDifference — Perform 3D difference
Synopsis
geometry ST_3DDifference(geometry geom1, geometry geom2);
Description
Returns that part of geom1 that is not part of geom2.
Availability: 2.2.0
This method needs SFCGAL backend.
This method implements the SQL/MM specification. SQL-MM IEC 13249-3: 5.1
This function supports 3d and will not drop the z-index.
This function supports Polyhedral surfaces.
This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).
Examples
3D images were generated using PostGIS ST_AsX3D and rendering in HTML using X3Dom HTML Javascript rendering library.
SELECT ST_Extrude(ST_Buffer(ST_GeomFromText('POINT(100 90)'),
50, 'quad_segs=2'),0,0,30) AS geom1,
ST_Extrude(ST_Buffer(ST_GeomFromText('POINT(80 80)'),
50, 'quad_segs=1'),0,0,30) AS geom2;
 Original 3D geometries overlaid. geom2 is the part that will be removed. |
SELECT ST_3DDifference(geom1,geom2)
FROM ( SELECT ST_Extrude(ST_Buffer(ST_GeomFromText('POINT(100 90)'),
50, 'quad_segs=2'),0,0,30) AS geom1,
ST_Extrude(ST_Buffer(ST_GeomFromText('POINT(80 80)'),
50, 'quad_segs=1'),0,0,30) AS geom2 ) As t;
 What's left after removing geom2 |