[postgis-tickets] r14458 - #2093, document new parameter

[Paul Ramsey]

Author: pramsey
Date: 2015-11-30 09:53:53 -0800 (Mon, 30 Nov 2015)
New Revision: 14458

Modified:
   branches/2.2/NEWS
   branches/2.2/doc/reference_processing.xml
Log:
#2093, document new parameter


Modified: branches/2.2/NEWS
===================================================================
--- branches/2.2/NEWS	2015-11-30 16:31:18 UTC (rev 14457)
+++ branches/2.2/NEWS	2015-11-30 17:53:53 UTC (rev 14458)
@@ -97,6 +97,7 @@
   - #2349, Support for encoded_polyline input/output (Kashif Rasul)
   - #2159, report libjson version from postgis_full_version()
   - #2770, ST_MemSize(raster)
+  - #2093, ST_Simplify(geom, tol, preserveCollapsed) new parameter
   - Add postgis_noop(raster)
   - Added missing variants of ST_TPI(), ST_TRI() and ST_Roughness()
   - Added GUC postgis.gdal_enabled_drivers to specify GDAL config

Modified: branches/2.2/doc/reference_processing.xml
===================================================================
--- branches/2.2/doc/reference_processing.xml	2015-11-30 16:31:18 UTC (rev 14457)
+++ branches/2.2/doc/reference_processing.xml	2015-11-30 17:53:53 UTC (rev 14458)
@@ -2647,6 +2647,7 @@
 			<funcdef>geometry <function>ST_Simplify</function></funcdef>
 			<paramdef><type>geometry</type> <parameter>geomA</parameter></paramdef>
 			<paramdef><type>float</type> <parameter>tolerance</parameter></paramdef>
+			<paramdef><type>boolean</type> <parameter>preserveCollapsed</parameter></paramdef>
 		  </funcprototype>
 		</funcsynopsis>
 	  </refsynopsisdiv>
@@ -2659,6 +2660,12 @@
 				any kind of geometry. Since simplification occurs on a
 				object-by-object basis you can also feed a GeometryCollection to
 				this function.</para>
+        
+    <para>The "preserve collapsed" flag will retain objects that would otherwise
+      be too small given the tolerance. For example, a 1m long line simplified with a 10m 
+      tolerance. If the preserve flag is given, the line will not disappear. This flag
+      is useful for rendering engines, to avoid having large numbers of very
+      small objects disappear from a map leaving surprising gaps.</para>
 
 		<note><para>Note that returned geometry might lose its
 				simplicity (see <xref linkend="ST_IsSimple" />)</para></note>