ST_CPAWithin

Name

ST_CPAWithin — Returns true if the closest point of approach of two trajectories is within the specified distance.

Synopsis

float8 ST_CPAWithin ( geometry track1 , geometry track2 , float8 maxdist ) ;

Description

Checks whether two moving objects have ever been within the specified maximum distance.

Inputs must be valid trajectories as checked by ST_IsValidTrajectory . False is returned if the trajectories do not overlap in their M ranges.

Availability: 2.2.0

This function supports 3d and will not drop the z-index.

Examples

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
)
SELECT ST_CPAWithin(a,b,2), ST_DistanceCPA(a,b) distance FROM inp;

 st_cpawithin |     distance
--------------+------------------
 t            | 1.96521473776207