st_intersects与st_overlaps [英] st_intersects Vs st_overlaps

问题描述

这两个查询之间有什么区别:

What is the difference between these two queries :

select a.gid, sum(length(b.the_geom)) 
  from polygons as a 
     , roads as b 
 where st_intersects(a.the_geom,b.the_geom) 
 group by a.gid ;

select a.gid, sum(length(b.the_geom)) 
  from polygons as a 
     , roads as b 
 where st_overlaps(a.the_geom,b.the_geom) 
 group by a.gid ;

第一个查询给出正确的输出，而第二个查询根本不检索任何行.与多边形相交的道路也重叠了，对吧?

Where the first query is giving the correct output whereas the second query retrieves no rows at all. The road that intersects the polygons also overlaps it, right?

推荐答案

来自PostGIS文档

From the documentation of PostGIS

http://postgis.net/docs/ST_Intersects.html

如果几何或地理共享空间的任何部分，则它们相交.重叠，触摸，所有暗示空间相交.如果有 前面提到的返回true，则几何在空间上 相交.

If a geometry or geography shares any portion of space then they intersect. Overlaps, Touches, Within all imply spatial intersection. If any of the aforementioned returns true, then the geometries also spatially intersect.

http://postgis.net/docs/ST_Overlaps.html

如果几何空间重叠"，则返回TRUE.我们的意思是 它们相交，但是一个并不完全包含另一个.

Returns TRUE if the Geometries "spatially overlap". By that we mean they intersect, but one does not completely contain another.

区别是:如果两个几何重叠100％，则它们不再重叠.

The difference is: If two geometries overlap 100%, they do not overlap any more.

这是一个POSTGIS示例:

Here is a POSTGIS example:

SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Intersects(a, b) As a_intersects_b, ST_Contains(b, a) As b_contains_a
FROM (SELECT 
    ST_Polygon(ST_GeomFromText('LINESTRING(1 1,3 1,3 3,1 1)'), 4326)  As a,
    ST_Polygon(ST_GeomFromText('LINESTRING(1 1,3 1,3 3,1 1)'), 4326)  As b)
    As foo;
    -- INTERSECT is TRUE, OVERLAP is FALSE because B equals A

    SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Intersects(a, b) As a_intersects_b, ST_Contains(b, a) As b_contains_a
FROM (SELECT 
    ST_Polygon(ST_GeomFromText('LINESTRING(1 1,3 1,3 3,1 1)'), 4326)  As a,
    ST_Polygon(ST_GeomFromText('LINESTRING(1 1,4 1,4 4,1 1)'), 4326)  As b)
    As foo;
    -- INTERSECT is TRUE, OVERLAP is FALSE because B contains A

    SELECT ST_Overlaps(a,b) As a_overlap_b, ST_Intersects(a, b) As a_intersects_b, ST_Contains(b, a) As b_contains_a
FROM (SELECT 
    ST_Polygon(ST_GeomFromText('LINESTRING(0 0,2 0,2 2,0 0)'), 4326)  As a,
    ST_Polygon(ST_GeomFromText('LINESTRING(1 1,3 1,3 3,1 1)'), 4326)  As b)
    As foo;
    -- INTERSECT is TRUE, OVERLAP is TRUE because not all of A intersects B and not all of B intersects A

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