[postgis-tickets] r15044 - Segmentize geography using equal length segments, (Hugo Mercier of Oslandia)

[Regina Obe]

Author: robe
Date: 2016-08-17 06:01:23 -0700 (Wed, 17 Aug 2016)
New Revision: 15044

Modified:
   trunk/NEWS
   trunk/liblwgeom/lwgeodetic.c
   trunk/regress/geography.sql
   trunk/regress/geography_expected
   trunk/regress/sfcgal/tickets_expected
   trunk/regress/tickets_expected
Log:
Segmentize geography using equal length segments, (Hugo Mercier of Oslandia)
Closes #3613
Closes #3539
Closes https://github.com/postgis/postgis/pull/90

Modified: trunk/NEWS
===================================================================
--- trunk/NEWS	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/NEWS	2016-08-17 13:01:23 UTC (rev 15044)
@@ -37,7 +37,8 @@
   - #3557, Geometry function costs based on query stats (Paul Norman)
   - #3591, Add support for BRIN indexes 
 		  (Giuseppe Broccolo of 2nd Quadrant, Julien Rouhaud and Ronan Dunklau of Dalibo)
-  - #3496 Make postgis non-relocateable (for extension install), schema qualify calls in functions (Regina Obe)
+  - #3496 Make postgis non-relocateable (for extension install), 
+		schema qualify calls in functions (Regina Obe)
 		Should resolve once and for all for extensions #3494, #3486, #3076 
 
  * Performance Enhancements *
@@ -47,6 +48,7 @@
     (Dan Baston)
   - #3400, Minor optimization of PIP routines (Dan Baston)
   - Make adding a line to topology interruptible (Sandro Santilli)
+  - #3613, Segmentize geography using equal length segments, (Hugo Mercier of Oslandia) 
 
 PostGIS 2.2.2
 2016/03/22

Modified: trunk/liblwgeom/lwgeodetic.c
===================================================================
--- trunk/liblwgeom/lwgeodetic.c	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/liblwgeom/lwgeodetic.c	2016-08-17 13:01:23 UTC (rev 15044)
@@ -1591,21 +1591,26 @@
 		{
 			int nsegs = 1 + d / max_seg_length;
 			int i;
-			double dx, dy, dzz = 0, dmm = 0;
-			g = g1;
-			dx = (g2.lat - g1.lat) / nsegs;
-			dy = (g2.lon - g1.lon) / nsegs;
+			double dzz = 0, dmm = 0;
+			double delta = d / nsegs;
 
 			/* The independent Z/M values on the ptarray */
 			if ( hasz ) dzz = (p2.z - p1.z) / nsegs;
 			if ( hasm ) dmm = (p2.m - p1.m) / nsegs;
 			
+			g = g1;
 			p = p1;
 			for ( i = 0; i < nsegs - 1; i++ )
 			{
+				GEOGRAPHIC_POINT gn;
+				double heading;
+
+				/* Compute the current heading to the destination */
+				heading = sphere_direction(&g, &g2, (nsegs-i) * delta);
 				/* Move one increment forwards */
-				g.lat += dx;
-				g.lon += dy;
+				sphere_project(&g, delta, heading, &gn);
+				g = gn;
+
 				p.x = rad2deg(g.lon);
 				p.y = rad2deg(g.lat);
 				if ( hasz )

Modified: trunk/regress/geography.sql
===================================================================
--- trunk/regress/geography.sql	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/regress/geography.sql	2016-08-17 13:01:23 UTC (rev 15044)
@@ -114,6 +114,9 @@
 dumped as (SELECT (st_dumppoints(geom)).path[1] as id, (st_dumppoints(geom)).geom from seg)
 SELECT 'segmentize_geography', max(st_distance(d1.geom::geography, d2.geom::geography, false))::int FROM dumped as d1, dumped as d2 where d2.id = d1.id + 1;
 
+-- Check that st_segmentize creates segments on the geodesic path
+SELECT 'segmentize_geography2', st_dwithin(st_pointn(st_segmentize('linestring(1 47,-64 47)'::geography, 3000000)::geometry, 2), 'SRID=4326;POINT(-31.5 51.81)'::geometry, 0.01);
+
 -- Clean up spatial_ref_sys
 DELETE FROM spatial_ref_sys WHERE srid IN (4269,4326);
 

Modified: trunk/regress/geography_expected
===================================================================
--- trunk/regress/geography_expected	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/regress/geography_expected	2016-08-17 13:01:23 UTC (rev 15044)
@@ -28,3 +28,4 @@
 #2422|1|1600|t|t|1400.230|1396.816|1400.230|1400.230
 #2422|1|1068|f|f|1400.230|1396.816|1400.230|1400.230
 segmentize_geography|49789
+segmentize_geography2|t

Modified: trunk/regress/sfcgal/tickets_expected
===================================================================
--- trunk/regress/sfcgal/tickets_expected	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/regress/sfcgal/tickets_expected	2016-08-17 13:01:23 UTC (rev 15044)
@@ -240,4 +240,4 @@
 #2110.1|f
 #2110.2|t
 #2110.3|t
-#2145|6792007
+#2145|6792004

Modified: trunk/regress/tickets_expected
===================================================================
--- trunk/regress/tickets_expected	2016-08-10 02:46:53 UTC (rev 15043)
+++ trunk/regress/tickets_expected	2016-08-17 13:01:23 UTC (rev 15044)
@@ -236,7 +236,7 @@
 #2110.1|f
 #2110.2|t
 #2110.3|t
-#2145|6792007
+#2145|6792004
 #2232|M 0 0 l 0 0 1 0 0 0 1 0 0 0
 #2307|MULTIPOLYGON(((-41.1932 -7.3257,-41.1616 -7.3257,-41.1569 -7.3257,-41.1569 -7.3483,-41.1932 -7.3483,-41.1932 -7.3257),(-41.1616 -7.3257,-41.1879 -7.3257,-41.1879 -7.3425,-41.1616 -7.3425,-41.1616 -7.3257)))
 #2409|GeometryCollection[B] with 2 elements