ST_ClosestPointOfApproach — 返回两个轨迹的最接近点处的度量值。
float8 ST_ClosestPointOfApproach(
geometry track1, geometry track2)
;
返回沿给定轨迹插补的点处于最小距离的最小度量值。
输入必须是由检查的有效轨迹 ST_IsValidTrajectory 。如果轨迹在其M范围内不重叠,则返回NULL。
看见 ST_LocateAlong 用于获得给定度量值的实际点数。
可用性:2.2.0
This function supports 3d and will not drop the z-index.
-- Return the time in which two objects moving between 10:00 and 11:00 -- are closest to each other and their distance at that point WITH inp AS ( SELECT ST_AddMeasure('LINESTRING Z (0 0 0, 10 0 5)'::geometry, extract(epoch from '2015-05-26 10:00'::timestamptz), extract(epoch from '2015-05-26 11:00'::timestamptz) ) a, ST_AddMeasure('LINESTRING Z (0 2 10, 12 1 2)'::geometry, extract(epoch from '2015-05-26 10:00'::timestamptz), extract(epoch from '2015-05-26 11:00'::timestamptz) ) b ), cpa AS ( SELECT ST_ClosestPointOfApproach(a,b) m FROM inp ), points AS ( SELECT ST_Force3DZ(ST_GeometryN(ST_LocateAlong(a,m),1)) pa, ST_Force3DZ(ST_GeometryN(ST_LocateAlong(b,m),1)) pb FROM inp, cpa ) SELECT to_timestamp(m) t, ST_Distance(pa,pb) distance FROM points, cpa; t | distance -------------------------------+------------------ 2015-05-26 10:45:31.034483+02 | 1.96036833151395