ST_Overlaps
Précédent  7.11.1. Relations topologiques  Suivant

Nom

ST_Overlaps — Teste si deux géométries ont la même dimension et se croisent, mais si chacune a au moins un point qui n'est pas dans l'autre

Synopsis

boolean ST_Overlaps(geometry A, geometry B);

Description

Renvoie TRUE si les géométries A et B se "chevauchent spatialement". Deux géométries se chevauchent si elles ont la même dimension, si leurs intérieurs se croisent dans cette dimension et si chacune a au moins un point à l'intérieur de l'autre (ou, de manière équivalente, si aucune des deux ne recouvre l'autre). La relation de chevauchement est symétrique et irréflexive.

En termes mathématiques : ST_Overlaps(A, B) ⇔ ( dim(A) = dim(B) = dim( Int(A) ⋂ Int(B) )). ∧ (A ⋂ B ≠ A) ∧ (A ⋂ B ≠ B)

[Note]

Cette fonction inclut une comparaison de la boîte englobante qui utilise tous les index disponibles sur les géométries. Pour éviter l'utilisation d'un index, utilisez la fonction _ST_Overlaps.

Effectué par le module GEOS

Amélioration : 3.0.0 a permis la prise en charge de GEOMETRYCOLLECTION

NOTE : il s'agit de la version "autorisée" qui renvoie un booléen et non un entier.

Cette méthode implémente la spécification OGC Simple Features Implementation Specification for SQL 1.1. s2.1.1.2 // s2.1.13.3

Cette méthode implémente la spécification SQL/MM. SQL-MM 3: 5.1.32

Exemples

ST_Overlaps renvoie TRUE dans les situations suivantes :

Two MultiPoints overlap when they share some, but not all, points.

Code
SELECT ST_Overlaps(a, b)
FROM (SELECT
  'MULTIPOINT ((20 20),(40 90),(80 130),(140 100),(110 40),(120 170),(150 70))'::geometry AS a,
  'MULTIPOINT ((180 10),(40 90),(80 130),(160 150),(110 40),(50 50),(50 160))'::geometry AS b
) AS example;
Export de raster
t
Figure
Geometry figure for visual-st-overlaps-01

Two LineStrings overlap along part of their paths.

Code
SELECT ST_Overlaps(a, b)
FROM (SELECT
  'LINESTRING (10 10,40 90,70 110,140 110,170 130,190 190)'::geometry AS a,
  'LINESTRING (10 190,50 130,90 110,130 110,160 70,180 10)'::geometry AS b
) AS example;
Export de raster
t
Figure
Geometry figure for visual-st-overlaps-02

Two Polygons overlap where their interiors intersect and neither contains the other.

Code
SELECT ST_Overlaps(a, b)
FROM (SELECT
  'POLYGON ((140 140,140 122,135 105,126 100,118 99,110 94,100 86,97 73,102 59,98 49,87 38,70 30,55 29,40 30,28 38,20 50,14 66,10 84,6 100,4 119,4 143,6 166,10 180,18 191,28 195,40 190,55 189,67 186,86 179,112 165,124 158,133 148,140 140),(48 177,40 177,30 174,24 166,22 159,25 155,30 153,40 154,45 157,52 162,53 169,51 174,48 177))'::geometry AS a,
  'POLYGON ((75 63,79 50,87 38,95 31,108 25,124 22,140 18,154 11,166 6,176 10,184 21,188 35,190 58,190 82,193 104,190 121,185 139,178 154,166 163,154 171,139 172,124 171,112 165,96 152,92 142,92 126,86 116,79 110,75 104,72 94,73 86,75 76,75 63))'::geometry AS b
) AS example;
Export de raster
t
Figure
Geometry figure for visual-st-overlaps-03

Un point sur une LineString est contenu, mais comme il a une dimension inférieure, il ne se chevauche pas et ne se croise pas.

Code
SELECT ST_Overlaps(a, b) AS overlaps, ST_Crosses(a, b) AS crosses,
       ST_Intersects(a, b) AS intersects, ST_Contains(b, a) AS b_contains_a
FROM (SELECT 'POINT (100 100)'::geometry As a,
             'LINESTRING (30 50,40 160,160 40,180 160)'::geometry  AS b) AS t
Export de raster
overlaps | crosses | intersects | b_contains_a
---------+----------------------+--------------
f        | f       | t          | t
Figure
Geometry figure for visual-st-overlaps-04

Une chaîne de lignes qui recouvre partiellement un polygone l'intersecte et le traverse, mais ne se chevauche pas car elle a des dimensions différentes.

Code
SELECT ST_Overlaps(a, b) AS overlaps, ST_Crosses(a, b) AS crosses,
       ST_Intersects(a, b) AS intersects, ST_Contains(a, b) AS contains
FROM (SELECT 'POLYGON ((40 170,90 30,180 100,40 170))'::geometry AS a,
             'LINESTRING(10 10,190 190)'::geometry AS b) AS t;
Export de raster
overlap | crosses | intersects | contains
---------+---------+------------+--------------
 f       | t       | t          | f
Figure
Geometry figure for visual-st-overlaps-05

Deux polygones qui se croisent mais dont aucun n'est contenu par l'autre se chevauchent, mais ne se croisent pas car leur intersection a la même dimension.

Code
SELECT ST_Overlaps(a, b) AS overlaps, ST_Crosses(a, b) AS crosses,
       ST_Intersects(a, b) AS intersects, ST_Contains(b, a) AS b_contains_a,
       ST_Dimension(a) AS dim_a, ST_Dimension(b) AS dim_b,
       ST_Dimension(ST_Intersection(a, b)) AS dim_int
FROM (SELECT 'POLYGON ((40 170,90 30,180 100,40 170))'::geometry AS a,
             'POLYGON ((110 180,20 60,130 90,110 180))'::geometry AS b) As t;
Export de raster
overlaps | crosses | intersects | b_contains_a | dim_a | dim_b | dim_int
----------+---------+------------+--------------+-------+-------+-----------
 t        | f       | t          | f            |     2 |     2 |       2
Figure
Geometry figure for visual-st-overlaps-06