PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ circ_tree_distance_tree()

double circ_tree_distance_tree ( const CIRC_NODE n1,
const CIRC_NODE n2,
const SPHEROID spheroid,
double  threshold 
)

Definition at line 554 of file lwgeodetic_tree.c.

References SPHEROID::a, SPHEROID::b, circ_tree_distance_tree_internal(), SPHEROID::radius, sphere_distance(), and spheroid_distance().

Referenced by geography_distance_cache_tolerance(), geography_tree_distance(), test_tree_circ_distance(), and test_tree_circ_distance_threshold().

555 {
556  double min_dist = FLT_MAX;
557  double max_dist = FLT_MAX;
558  GEOGRAPHIC_POINT closest1, closest2;
559  /* Quietly decrease the threshold just a little to avoid cases where */
560  /* the actual spheroid distance is larger than the sphere distance */
561  /* causing the return value to be larger than the threshold value */
562  double threshold_radians = 0.95 * threshold / spheroid->radius;
563 
564  circ_tree_distance_tree_internal(n1, n2, threshold_radians, &min_dist, &max_dist, &closest1, &closest2);
565 
566  /* Spherical case */
567  if ( spheroid->a == spheroid->b )
568  {
569  return spheroid->radius * sphere_distance(&closest1, &closest2);
570  }
571  else
572  {
573  return spheroid_distance(&closest1, &closest2, spheroid);
574  }
575 }
double sphere_distance(const GEOGRAPHIC_POINT *s, const GEOGRAPHIC_POINT *e)
Given two points on a unit sphere, calculate their distance apart in radians.
Definition: lwgeodetic.c:898
double b
Definition: liblwgeom.h:298
double radius
Definition: liblwgeom.h:302
static double circ_tree_distance_tree_internal(const CIRC_NODE *n1, const CIRC_NODE *n2, double threshold, double *min_dist, double *max_dist, GEOGRAPHIC_POINT *closest1, GEOGRAPHIC_POINT *closest2)
Point in spherical coordinates on the world.
Definition: lwgeodetic.h:32
double a
Definition: liblwgeom.h:297
double spheroid_distance(const GEOGRAPHIC_POINT *a, const GEOGRAPHIC_POINT *b, const SPHEROID *spheroid)
Computes the shortest distance along the surface of the spheroid between two points.
Definition: lwspheroid.c:172
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