PostGIS  2.2.8dev-r@@SVN_REVISION@@

◆ lwgeom_distance_spheroid()

double lwgeom_distance_spheroid ( const LWGEOM lwgeom1,
const LWGEOM lwgeom2,
const SPHEROID spheroid,
double  tolerance 
)

Calculate the geodetic distance from lwgeom1 to lwgeom2 on the spheroid.

A spheroid with major axis == minor axis will be treated as a sphere. Pass in a tolerance in spheroid units.

Calculate the geodetic distance from lwgeom1 to lwgeom2 on the spheroid.

Return immediately when the calulated distance drops below the tolerance (useful for dwithin calculations). Return a negative distance for incalculable cases.

Definition at line 2081 of file lwgeodetic.c.

References LWGEOM::bbox, distance(), gbox_init(), gbox_overlaps(), LWCOLLECTION::geoms, getPoint2d_cp(), LINETYPE, LW_FALSE, LW_TRUE, LWDEBUG, LWDEBUGF, lwerror(), lwgeom_calculate_gbox_geodetic(), lwgeom_is_empty(), lwpoly_covers_point2d(), lwtype_is_collection(), lwtype_name(), LWCOLLECTION::ngeoms, LWPOLY::nrings, LWPOINT::point, LWLINE::points, POINTTYPE, POLYGONTYPE, ptarray_distance_spheroid(), LWPOLY::rings, and LWGEOM::type.

Referenced by geography_distance(), geography_distance_knn(), geography_distance_uncached(), geography_dwithin(), geography_dwithin_uncached(), geometry_distance_spheroid(), test_lwgeom_distance_sphere(), test_tree_circ_distance(), and test_tree_circ_distance_threshold().

2082 {
2083  uint8_t type1, type2;
2084  int check_intersection = LW_FALSE;
2085  GBOX gbox1, gbox2;
2086 
2087  gbox_init(&gbox1);
2088  gbox_init(&gbox2);
2089 
2090  assert(lwgeom1);
2091  assert(lwgeom2);
2092 
2093  LWDEBUGF(4, "entered function, tolerance %.8g", tolerance);
2094 
2095  /* What's the distance to an empty geometry? We don't know.
2096  Return a negative number so the caller can catch this case. */
2097  if ( lwgeom_is_empty(lwgeom1) || lwgeom_is_empty(lwgeom2) )
2098  {
2099  return -1.0;
2100  }
2101 
2102  type1 = lwgeom1->type;
2103  type2 = lwgeom2->type;
2104 
2105  /* Make sure we have boxes */
2106  if ( lwgeom1->bbox )
2107  gbox1 = *(lwgeom1->bbox);
2108  else
2109  lwgeom_calculate_gbox_geodetic(lwgeom1, &gbox1);
2110 
2111  /* Make sure we have boxes */
2112  if ( lwgeom2->bbox )
2113  gbox2 = *(lwgeom2->bbox);
2114  else
2115  lwgeom_calculate_gbox_geodetic(lwgeom2, &gbox2);
2116 
2117  /* If the boxes aren't disjoint, we have to check for edge intersections */
2118  if ( gbox_overlaps(&gbox1, &gbox2) )
2119  check_intersection = LW_TRUE;
2120 
2121  /* Point/line combinations can all be handled with simple point array iterations */
2122  if ( ( type1 == POINTTYPE || type1 == LINETYPE ) &&
2123  ( type2 == POINTTYPE || type2 == LINETYPE ) )
2124  {
2125  POINTARRAY *pa1, *pa2;
2126 
2127  if ( type1 == POINTTYPE )
2128  pa1 = ((LWPOINT*)lwgeom1)->point;
2129  else
2130  pa1 = ((LWLINE*)lwgeom1)->points;
2131 
2132  if ( type2 == POINTTYPE )
2133  pa2 = ((LWPOINT*)lwgeom2)->point;
2134  else
2135  pa2 = ((LWLINE*)lwgeom2)->points;
2136 
2137  return ptarray_distance_spheroid(pa1, pa2, spheroid, tolerance, check_intersection);
2138  }
2139 
2140  /* Point/Polygon cases, if point-in-poly, return zero, else return distance. */
2141  if ( ( type1 == POLYGONTYPE && type2 == POINTTYPE ) ||
2142  ( type2 == POLYGONTYPE && type1 == POINTTYPE ) )
2143  {
2144  const POINT2D *p;
2145  LWPOLY *lwpoly;
2146  LWPOINT *lwpt;
2147  double distance = FLT_MAX;
2148  int i;
2149 
2150  if ( type1 == POINTTYPE )
2151  {
2152  lwpt = (LWPOINT*)lwgeom1;
2153  lwpoly = (LWPOLY*)lwgeom2;
2154  }
2155  else
2156  {
2157  lwpt = (LWPOINT*)lwgeom2;
2158  lwpoly = (LWPOLY*)lwgeom1;
2159  }
2160  p = getPoint2d_cp(lwpt->point, 0);
2161 
2162  /* Point in polygon implies zero distance */
2163  if ( lwpoly_covers_point2d(lwpoly, p) )
2164  {
2165  return 0.0;
2166  }
2167 
2168  /* Not inside, so what's the actual distance? */
2169  for ( i = 0; i < lwpoly->nrings; i++ )
2170  {
2171  double ring_distance = ptarray_distance_spheroid(lwpoly->rings[i], lwpt->point, spheroid, tolerance, check_intersection);
2172  if ( ring_distance < distance )
2173  distance = ring_distance;
2174  if ( distance < tolerance )
2175  return distance;
2176  }
2177  return distance;
2178  }
2179 
2180  /* Line/polygon case, if start point-in-poly, return zero, else return distance. */
2181  if ( ( type1 == POLYGONTYPE && type2 == LINETYPE ) ||
2182  ( type2 == POLYGONTYPE && type1 == LINETYPE ) )
2183  {
2184  const POINT2D *p;
2185  LWPOLY *lwpoly;
2186  LWLINE *lwline;
2187  double distance = FLT_MAX;
2188  int i;
2189 
2190  if ( type1 == LINETYPE )
2191  {
2192  lwline = (LWLINE*)lwgeom1;
2193  lwpoly = (LWPOLY*)lwgeom2;
2194  }
2195  else
2196  {
2197  lwline = (LWLINE*)lwgeom2;
2198  lwpoly = (LWPOLY*)lwgeom1;
2199  }
2200  p = getPoint2d_cp(lwline->points, 0);
2201 
2202  LWDEBUG(4, "checking if a point of line is in polygon");
2203 
2204  /* Point in polygon implies zero distance */
2205  if ( lwpoly_covers_point2d(lwpoly, p) )
2206  return 0.0;
2207 
2208  LWDEBUG(4, "checking ring distances");
2209 
2210  /* Not contained, so what's the actual distance? */
2211  for ( i = 0; i < lwpoly->nrings; i++ )
2212  {
2213  double ring_distance = ptarray_distance_spheroid(lwpoly->rings[i], lwline->points, spheroid, tolerance, check_intersection);
2214  LWDEBUGF(4, "ring[%d] ring_distance = %.8g", i, ring_distance);
2215  if ( ring_distance < distance )
2216  distance = ring_distance;
2217  if ( distance < tolerance )
2218  return distance;
2219  }
2220  LWDEBUGF(4, "all rings checked, returning distance = %.8g", distance);
2221  return distance;
2222 
2223  }
2224 
2225  /* Polygon/polygon case, if start point-in-poly, return zero, else return distance. */
2226  if ( ( type1 == POLYGONTYPE && type2 == POLYGONTYPE ) ||
2227  ( type2 == POLYGONTYPE && type1 == POLYGONTYPE ) )
2228  {
2229  const POINT2D *p;
2230  LWPOLY *lwpoly1 = (LWPOLY*)lwgeom1;
2231  LWPOLY *lwpoly2 = (LWPOLY*)lwgeom2;
2232  double distance = FLT_MAX;
2233  int i, j;
2234 
2235  /* Point of 2 in polygon 1 implies zero distance */
2236  p = getPoint2d_cp(lwpoly1->rings[0], 0);
2237  if ( lwpoly_covers_point2d(lwpoly2, p) )
2238  return 0.0;
2239 
2240  /* Point of 1 in polygon 2 implies zero distance */
2241  p = getPoint2d_cp(lwpoly2->rings[0], 0);
2242  if ( lwpoly_covers_point2d(lwpoly1, p) )
2243  return 0.0;
2244 
2245  /* Not contained, so what's the actual distance? */
2246  for ( i = 0; i < lwpoly1->nrings; i++ )
2247  {
2248  for ( j = 0; j < lwpoly2->nrings; j++ )
2249  {
2250  double ring_distance = ptarray_distance_spheroid(lwpoly1->rings[i], lwpoly2->rings[j], spheroid, tolerance, check_intersection);
2251  if ( ring_distance < distance )
2252  distance = ring_distance;
2253  if ( distance < tolerance )
2254  return distance;
2255  }
2256  }
2257  return distance;
2258  }
2259 
2260  /* Recurse into collections */
2261  if ( lwtype_is_collection(type1) )
2262  {
2263  int i;
2264  double distance = FLT_MAX;
2265  LWCOLLECTION *col = (LWCOLLECTION*)lwgeom1;
2266 
2267  for ( i = 0; i < col->ngeoms; i++ )
2268  {
2269  double geom_distance = lwgeom_distance_spheroid(col->geoms[i], lwgeom2, spheroid, tolerance);
2270  if ( geom_distance < distance )
2271  distance = geom_distance;
2272  if ( distance < tolerance )
2273  return distance;
2274  }
2275  return distance;
2276  }
2277 
2278  /* Recurse into collections */
2279  if ( lwtype_is_collection(type2) )
2280  {
2281  int i;
2282  double distance = FLT_MAX;
2283  LWCOLLECTION *col = (LWCOLLECTION*)lwgeom2;
2284 
2285  for ( i = 0; i < col->ngeoms; i++ )
2286  {
2287  double geom_distance = lwgeom_distance_spheroid(lwgeom1, col->geoms[i], spheroid, tolerance);
2288  if ( geom_distance < distance )
2289  distance = geom_distance;
2290  if ( distance < tolerance )
2291  return distance;
2292  }
2293  return distance;
2294  }
2295 
2296 
2297  lwerror("arguments include unsupported geometry type (%s, %s)", lwtype_name(type1), lwtype_name(type1));
2298  return -1.0;
2299 
2300 }
#define LINETYPE
Definition: liblwgeom.h:71
GBOX * bbox
Definition: liblwgeom.h:382
static double ptarray_distance_spheroid(const POINTARRAY *pa1, const POINTARRAY *pa2, const SPHEROID *s, double tolerance, int check_intersection)
Definition: lwgeodetic.c:1731
double lwgeom_distance_spheroid(const LWGEOM *lwgeom1, const LWGEOM *lwgeom2, const SPHEROID *spheroid, double tolerance)
Calculate the distance between two LWGEOMs, using the coordinates are longitude and latitude...
Definition: lwgeodetic.c:2081
#define POLYGONTYPE
Definition: liblwgeom.h:72
#define LWDEBUG(level, msg)
Definition: lwgeom_log.h:50
POINTARRAY * point
Definition: liblwgeom.h:395
const char * lwtype_name(uint8_t type)
Return the type name string associated with a type number (e.g.
Definition: lwutil.c:188
void gbox_init(GBOX *gbox)
Zero out all the entries in the GBOX.
Definition: g_box.c:36
#define LW_FALSE
Definition: liblwgeom.h:62
const POINT2D * getPoint2d_cp(const POINTARRAY *pa, int n)
Returns a POINT2D pointer into the POINTARRAY serialized_ptlist, suitable for reading from...
Definition: lwgeom_api.c:472
#define LW_TRUE
Return types for functions with status returns.
Definition: liblwgeom.h:61
LWGEOM ** geoms
Definition: liblwgeom.h:493
int lwgeom_calculate_gbox_geodetic(const LWGEOM *geom, GBOX *gbox)
Calculate the geodetic bounding box for an LWGEOM.
Definition: lwgeodetic.c:2615
POINTARRAY ** rings
Definition: liblwgeom.h:441
int lwtype_is_collection(uint8_t type)
Determine whether a type number is a collection or not.
Definition: lwgeom.c:999
int nrings
Definition: liblwgeom.h:439
Datum distance(PG_FUNCTION_ARGS)
#define POINTTYPE
LWTYPE numbers, used internally by PostGIS.
Definition: liblwgeom.h:70
int gbox_overlaps(const GBOX *g1, const GBOX *g2)
Return LW_TRUE if the GBOX overlaps, LW_FALSE otherwise.
Definition: g_box.c:260
uint8_t type
Definition: liblwgeom.h:380
int lwpoly_covers_point2d(const LWPOLY *poly, const POINT2D *pt_to_test)
Given a polygon (lon/lat decimal degrees) and point (lon/lat decimal degrees) and a guaranteed outsid...
Definition: lwgeodetic.c:2387
int lwgeom_is_empty(const LWGEOM *geom)
Return true or false depending on whether a geometry is an "empty" geometry (no vertices members) ...
Definition: lwgeom.c:1297
#define LWDEBUGF(level, msg,...)
Definition: lwgeom_log.h:55
void lwerror(const char *fmt,...)
Write a notice out to the error handler.
Definition: lwutil.c:74
POINTARRAY * points
Definition: liblwgeom.h:406
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