CG_Tesselate
이전  8.3. SFCGAL Processing and Relationship Functions  다음

제목

CG_Tesselate — 폴리곤 또는 다면체 표면의 표면 다듬기(tessellation) 작업을 수행한 다음 TIN 또는 TIN 집합으로 반환합니다.

요약

geometry CG_Tesselate(geometry geom);

설명

[멀티]폴리곤 또는 다면체 표면 같은 표면 도형을 입력받아 삼각형을 이용한 다듬기(모자이크) 과정을 거친 TIN 표현식을 반환합니다.

[참고]

ST_TriangulatePolygon does similar to this function except that it returns a geometry collection of polygons instead of a TIN and also only works with 2D geometries.

Availability: 3.5.0

This method needs SFCGAL backend.

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).

예시

Tessellation divides each face of a cube into triangles.

Code
WITH data AS (
  SELECT 'POLYHEDRALSURFACE Z( ((0 0 0,0 0 1,0 1 1,0 1 0,0 0 0)),
((0 0 0,0 1 0,1 1 0,1 0 0,0 0 0)),((0 0 0,1 0 0,1 0 1,0 0 1,0 0 0)),
((1 1 0,1 1 1,1 0 1,1 0 0,1 1 0)),
((0 1 0,0 1 1,1 1 1,1 1 0,0 1 0)),((0 0 1,1 0 1,1 1 1,0 1 1,0 0 1)) )'::geometry AS cube
)
SELECT CG_Tesselate(cube) AS tessellation
FROM data;
래스터 출력
TIN Z (((0 0 0,0 0 1,0 1 1,0 0 0)),((0 1 0,0 0 0,0 1 1,0 1 0)),((0 0 0,0 1 0,1 1 0,0 0 0)),((1 0 0,0 0 0,1 1 0,1 0 0)),((0 0 1,1 0 0,1 0 1,0 0 1)),((0 0 1,0 0 0,1 0 0,0 0 1)),((1 1 0,1 1 1,1 0 1,1 1 0)),((1 0 0,1 1 0,1 0 1,1 0 0)),((0 1 0,0 1 1,1 1 1,0 1 0)),((1 1 0,0 1 0,1 1 1,1 1 0)),((0 1 1,1 0 1,1 1 1,0 1 1)),((0 1 1,0 0 1,1 0 1,0 1 1)))
Figure
Geometry figure for visual-cg-tesselate-01

Tessellation of a Polygon.

Code
WITH data AS (
  SELECT 'POLYGON((10 190,10 70,80 70,80 130,50 160,120 160,120 190,10 190))'::geometry AS polygon
)
SELECT polygon AS input_polygon,
       CG_Tesselate(polygon) AS tessellation
FROM data;
래스터 출력
POLYGON((10 190,10 70,80 70,80 130,50 160,120 160,120 190,10 190)) | TIN(((80 130,10 70,80 70,80 130)),((50 160,10 190,10 70,50 160)),((80 130,50 160,10 70,80 130)),((120 160,120 190,50 160,120 160)),((120 190,10 190,50 160,120 190)))
Figure
Geometry figure for visual-cg-tesselate-02