CG_ConstrainedDelaunayTriangles
Précédent  8.3. Fonctions de traitement et de relation SFCGAL  Suivant

Nom

CG_ConstrainedDelaunayTriangles — Renvoie une triangulation de Delaunay contrainte autour de la géométrie d'entrée donnée.

Synopsis

geometry CG_ConstrainedDelaunayTriangles(geometry g1);

Description

Renvoie un Constrained Delaunay triangulation autour des sommets de la géométrie d'entrée. Le résultat est un TIN.

Cette méthode nécessite le backend SFCGAL.

Disponibilité : 3.0.0

Cette fonction prend en charge la 3D et ne supprime pas l'indice z.

Exemples

Constrained Delaunay triangulation of the polygon and buffered point.

Code
SELECT
  CG_ConstrainedDelaunayTriangles(
    ST_Union(
      'POLYGON((175 150,20 40,50 60,125 100,175 150))'::geometry,
      ST_Buffer('POINT(110 170)'::geometry, 20)
    )
  );
Export de raster
TIN(((50 60,175 150,20 40,50 60)),((125 100,50 60,20 40,125 100)),((50 60,125 100,175 150,50 60)),((130 170,129.6 166.1,175 150,130 170)),((128.5 162.3,175 150,129.6 166.1,128.5 162.3)),((130 170,124.1 155.9,129.6 166.1,130 170)),((126.6 158.9,175 150,128.5 162.3,126.6 158.9)),((129.6 166.1,126.6 158.9,128.5 162.3,129.6 166.1)),((124.1 155.9,175 150,126.6 158.9,124.1 155.9)),((129.6 166.1,124.1 155.9,126.6 158.9,129.6 166.1)),((121.1 153.4,175 150,124.1 155.9,121.1 153.4)),((110 150,121.1 153.4,124.1 155.9,110 150)),((117.7 151.5,175 150,121.1 153.4,117.7 151.5)),((113.9 150.4,117.7 151.5,121.1 153.4,113.9 150.4)),((113.9 150.4,175 150,117.7 151.5,113.9 150.4)),((20 40,113.9 150.4,110 150,20 40)),((20 40,175 150,113.9 150.4,20 40)),((20 40,110 150,106.1 150.4,20 40)),((113.9 150.4,121.1 153.4,110 150,113.9 150.4)),((20 40,106.1 150.4,102.3 151.5,20 40)),((110 150,124.1 155.9,128.5 177.7,110 150)),((20 40,102.3 151.5,98.9 153.4,20 40)),((106.1 150.4,110 150,98.9 153.4,106.1 150.4)),((20 40,98.9 153.4,95.9 155.9,20 40)),((102.3 151.5,106.1 150.4,98.9 153.4,102.3 151.5)),((20 40,95.9 155.9,93.4 158.9,20 40)),((98.9 153.4,110 150,95.9 155.9,98.9 153.4)),((20 40,93.4 158.9,91.5 162.3,20 40)),((95.9 155.9,110 150,102.3 188.5,95.9 155.9)),((20 40,91.5 162.3,90.4 166.1,20 40)),((93.4 158.9,95.9 155.9,91.5 162.3,93.4 158.9)),((20 40,90.4 166.1,90 170,20 40)),((91.5 162.3,95.9 155.9,90 170,91.5 162.3)),((20 40,90 170,90.4 173.9,20 40)),((90.4 166.1,91.5 162.3,90 170,90.4 166.1)),((20 40,90.4 173.9,91.5 177.7,20 40)),((90 170,95.9 155.9,102.3 188.5,90 170)),((90.4 173.9,90 170,91.5 177.7,90.4 173.9)),((91.5 177.7,90 170,102.3 188.5,91.5 177.7)),((93.4 181.1,91.5 177.7,95.9 184.1,93.4 181.1)),((95.9 184.1,91.5 177.7,102.3 188.5,95.9 184.1)),((98.9 186.6,95.9 184.1,102.3 188.5,98.9 186.6)),((102.3 188.5,110 150,128.5 177.7,102.3 188.5)),((106.1 189.6,102.3 188.5,110 190,106.1 189.6)),((110 190,102.3 188.5,117.7 188.5,110 190)),((113.9 189.6,110 190,117.7 188.5,113.9 189.6)),((117.7 188.5,102.3 188.5,128.5 177.7,117.7 188.5)),((121.1 186.6,124.1 184.1,175 150,121.1 186.6)),((121.1 186.6,117.7 188.5,124.1 184.1,121.1 186.6)),((124.1 184.1,126.6 181.1,175 150,124.1 184.1)),((124.1 184.1,117.7 188.5,128.5 177.7,124.1 184.1)),((126.6 181.1,128.5 177.7,175 150,126.6 181.1)),((126.6 181.1,124.1 184.1,128.5 177.7,126.6 181.1)),((128.5 177.7,129.6 173.9,175 150,128.5 177.7)),((128.5 177.7,124.1 155.9,130 170,128.5 177.7)),((129.6 173.9,130 170,175 150,129.6 173.9)),((129.6 173.9,128.5 177.7,130 170,129.6 173.9)))
Figure
Geometry figure for visual-cg-constraineddelaunaytriangles-01

ST_DelaunayTriangles applied to the same input. Triangle edges cross polygon boundaries.

Code
SELECT
  ST_DelaunayTriangles(
    ST_Union(
      'POLYGON((175 150,20 40,50 60,125 100,175 150))'::geometry,
      ST_Buffer('POINT(110 170)'::geometry, 20)
    )
  );
Export de raster
GEOMETRYCOLLECTION(POLYGON((95.9 184.1,93.4 181.1,95.9 155.9,95.9 184.1)), POLYGON((95.9 184.1,95.9 155.9,102.3 188.5,95.9 184.1)), POLYGON((95.9 184.1,102.3 188.5,98.9 186.6,95.9 184.1)), POLYGON((102.3 188.5,95.9 155.9,98.9 153.4,102.3 188.5)), POLYGON((102.3 188.5,98.9 153.4,102.3 151.5,102.3 188.5)), POLYGON((102.3 188.5,102.3 151.5,106.1 189.6,102.3 188.5)), POLYGON((106.1 189.6,102.3 151.5,106.1 150.4,106.1 189.6)), POLYGON((106.1 189.6,106.1 150.4,110 190,106.1 189.6)), POLYGON((110 190,106.1 150.4,110 150,110 190)), POLYGON((110 190,110 150,117.7 188.5,110 190)), POLYGON((110 190,117.7 188.5,113.9 189.6,110 190)), POLYGON((117.7 188.5,110 150,121.1 153.4,117.7 188.5)), POLYGON((117.7 188.5,121.1 153.4,121.1 186.6,117.7 188.5)), POLYGON((121.1 186.6,121.1 153.4,124.1 155.9,121.1 186.6)), POLYGON((121.1 186.6,124.1 155.9,124.1 184.1,121.1 186.6)), POLYGON((121.1 186.6,124.1 184.1,175 150,121.1 186.6)), POLYGON((175 150,124.1 184.1,126.6 181.1,175 150)), POLYGON((175 150,126.6 181.1,128.5 177.7,175 150)), POLYGON((175 150,128.5 177.7,129.6 173.9,175 150)), POLYGON((175 150,129.6 173.9,130 170,175 150)), POLYGON((175 150,130 170,129.6 166.1,175 150)), POLYGON((175 150,129.6 166.1,128.5 162.3,175 150)), POLYGON((175 150,128.5 162.3,126.6 158.9,175 150)), POLYGON((175 150,126.6 158.9,124.1 155.9,175 150)), POLYGON((175 150,124.1 155.9,125 100,175 150)), POLYGON((125 100,124.1 155.9,121.1 153.4,125 100)), POLYGON((125 100,121.1 153.4,117.7 151.5,125 100)), POLYGON((125 100,117.7 151.5,113.9 150.4,125 100)), POLYGON((125 100,113.9 150.4,110 150,125 100)), POLYGON((125 100,110 150,106.1 150.4,125 100)), POLYGON((125 100,106.1 150.4,102.3 151.5,125 100)), POLYGON((125 100,102.3 151.5,98.9 153.4,125 100)), POLYGON((125 100,98.9 153.4,50 60,125 100)), POLYGON((125 100,50 60,20 40,125 100)), POLYGON((20 40,50 60,90.4 166.1,20 40)), POLYGON((20 40,90.4 166.1,90 170,20 40)), POLYGON((20 40,90 170,90.4 173.9,20 40)), POLYGON((20 40,90.4 173.9,91.5 177.7,20 40)), POLYGON((91.5 177.7,90.4 173.9,90 170,91.5 177.7)), POLYGON((91.5 177.7,90 170,91.5 162.3,91.5 177.7)), POLYGON((91.5 177.7,91.5 162.3,93.4 158.9,91.5 177.7)), POLYGON((91.5 177.7,93.4 158.9,93.4 181.1,91.5 177.7)), POLYGON((93.4 181.1,93.4 158.9,95.9 155.9,93.4 181.1)), POLYGON((95.9 155.9,93.4 158.9,50 60,95.9 155.9)), POLYGON((95.9 155.9,50 60,98.9 153.4,95.9 155.9)), POLYGON((50 60,93.4 158.9,91.5 162.3,50 60)), POLYGON((50 60,91.5 162.3,90.4 166.1,50 60)), POLYGON((90.4 166.1,91.5 162.3,90 170,90.4 166.1)), POLYGON((110 150,113.9 150.4,121.1 153.4,110 150)), POLYGON((121.1 153.4,113.9 150.4,117.7 151.5,121.1 153.4)), POLYGON((124.1 155.9,126.6 158.9,129.6 166.1,124.1 155.9)), POLYGON((124.1 155.9,129.6 166.1,128.5 177.7,124.1 155.9)), POLYGON((124.1 155.9,128.5 177.7,124.1 184.1,124.1 155.9)), POLYGON((124.1 184.1,128.5 177.7,126.6 181.1,124.1 184.1)), POLYGON((128.5 177.7,129.6 166.1,130 170,128.5 177.7)), POLYGON((128.5 177.7,130 170,129.6 173.9,128.5 177.7)), POLYGON((129.6 166.1,126.6 158.9,128.5 162.3,129.6 166.1)))
Figure
Geometry figure for visual-cg-constraineddelaunaytriangles-02