[GRASS-SVN] r53459 - grass/trunk/vector/v.distance

[svn_grass at osgeo.org]

Author: mmetz
Date: 2012-10-17 23:50:52 -0700 (Wed, 17 Oct 2012)
New Revision: 53459

Modified:
   grass/trunk/vector/v.distance/main.c
   grass/trunk/vector/v.distance/v.distance.html
Log:
v.distance: manual update, bug fix

Modified: grass/trunk/vector/v.distance/main.c
===================================================================
--- grass/trunk/vector/v.distance/main.c	2012-10-17 21:46:27 UTC (rev 53458)
+++ grass/trunk/vector/v.distance/main.c	2012-10-18 06:50:52 UTC (rev 53459)
@@ -308,7 +308,7 @@
     Vect_set_open_level(2);
     Vect_open_old2(&To, opt.to->answer, "", opt.to_field->answer);
 
-    ntolines = Vect_get_num_primitives(&To, from_type);
+    ntolines = Vect_get_num_primitives(&To, to_type);
     ntoareas = 0;
     if (to_type & GV_AREA)
 	ntoareas = Vect_get_num_areas(&To);
@@ -714,6 +714,10 @@
 		G_debug(3, "  %d areas in box", aList->n_values);
 
 		for (i = 0; i < aList->n_values; i++) {
+		    /* ignore isles OK ? */
+		    if (Vect_get_area_centroid(&To, aList->id[i]) == 0)
+			continue;
+
 		    tmp_tcat = -1;
 
 		    line2area(&To, FPoints, ftype, aList->id[i], &aList->box[i],
@@ -832,7 +836,10 @@
 	    G_debug(3, "farea = %d", area);
 	    G_percent(area, nfromareas, 2);
 
-	    Vect_get_area_cats(&From, area, FCats);
+	    if (Vect_get_area_cats(&From, area, FCats) == 1)
+		/* ignore isles OK ? */
+		continue;
+
 	    Vect_cat_get(FCats, from_field, &fcat);
 	    if (fcat < 0 && !do_all)
 		continue;
@@ -970,6 +977,10 @@
 		    tarea = aList->id[i];
 		    G_debug(4, "%d: 'to' area id %d", i, tarea);
 
+		    /* ignore isles OK ? */
+		    if (Vect_get_area_centroid(&To, tarea) == 0)
+			continue;
+
 		    Vect_get_area_points(&To, tarea, TPoints);
 		    
 		    ttype = GV_BOUNDARY;

Modified: grass/trunk/vector/v.distance/v.distance.html
===================================================================
--- grass/trunk/vector/v.distance/v.distance.html	2012-10-17 21:46:27 UTC (rev 53458)
+++ grass/trunk/vector/v.distance/v.distance.html	2012-10-18 06:50:52 UTC (rev 53459)
@@ -37,7 +37,12 @@
 locations with zero distance, and the common location would then be the 
 result of an overlay consisting of several points, lines, or areas.
 <em>v.distance</em> selects in these cases a single point, and does not 
-create an overlay like <em>v.overlay</em>.
+create an overlay like <em>v.overlay</em>. In this implementation, any 
+shared point is as good as any other. Calculating an intersection is 
+costlier than to check if a vertex is inside a polygon. For example, if 
+a vertex of the boundary of the 'to' area is inside the 'from' area, it 
+is a common location. For speed reasons, the distance is then set to 
+zero and no further tests are done.
 
 
 <h2>NOTES</h2>
@@ -49,7 +54,7 @@
 
 <!-- needs Vect_line_geodesic_distance()
 <p>In lat-long locations <em>v.distance</em> gives distances 
-(<em>dist</em> and <em>to_along</em>) in meters not in degrees 
+(<em>dist</em> and <em>to_along</em>) not in degrees but in meters  
 calculated as geodesic distances on a sphere.
 -->