From: Bborie Park <bkpark at ucdavis.edu>
Date: Wed, 24 Oct 2012 22:22:04 +0000 (+0000)
Subject: Preprocess input geometry for clipping raster by using the intersection
X-Git-Tag: 2.1.0beta2~464
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=34ee5c00a7e3edc8da0e22772aa4fc860214b1b9;p=postgis

Preprocess input geometry for clipping raster by using the intersection
of the input geometry and the convex hull of the raster. Ticket #1989

git-svn-id: http://svn.osgeo.org/postgis/trunk@10551 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/NEWS b/NEWS
index b7b2754dd..e12d2ae36 100644
--- a/NEWS
+++ b/NEWS
@@ -50,6 +50,7 @@ PostGIS 2.1.0
   - #1364, ST_Union(raster, ...) aggregate function rewritten in C
   - #1661, Add aggregate variant of ST_SameAlignment
   - #1719, Add support for Point and GeometryCollection ST_MakeValid inputs
+  - #1780, support ST_GeoHash for geography
   - #1796, Big performance boost for distance calculations in geography
   - #1802, improved function interruptibility.
   - #1856, tiger geocoder: reverse geocoder rating setting for prefer 
@@ -57,7 +58,8 @@ PostGIS 2.1.0
   - #1938, Refactor basic ST_AddBand to add multiple new bands in one call
   - #1978, wrong answer when calculating length of a closed circular 
            arc (circle)
-  - #1780, support ST_GeoHash for geography
+  - #1989, Preprocess input geometry to just intersection with raster
+           to be clipped
   - #2021, Added multi-band support to ST_Union(raster, ...) aggregate function
   - #2006, better support of ST_Area(geography) over poles and dateline
   - TopologySummary output now includes unregistered layers and a count
diff --git a/raster/rt_pg/rtpostgis.sql.in.c b/raster/rt_pg/rtpostgis.sql.in.c
index 6f7ec96ba..c21196efa 100644
--- a/raster/rt_pg/rtpostgis.sql.in.c
+++ b/raster/rt_pg/rtpostgis.sql.in.c
@@ -5461,6 +5461,7 @@ CREATE OR REPLACE FUNCTION st_clip(rast raster, band int, geom geometry, nodatav
 	RETURNS raster
 	AS $$
 	DECLARE
+		g geometry;
 		newrast raster;
 		geomrast raster;
 		numband int;
@@ -5494,7 +5495,8 @@ CREATE OR REPLACE FUNCTION st_clip(rast raster, band int, geom geometry, nodatav
 		newextent := CASE WHEN crop THEN 'INTERSECTION' ELSE 'FIRST' END;
 
 		-- Convert the geometry to a raster
-		geomrast := ST_AsRaster(geom, rast, ST_BandPixelType(rast, band), 1, newnodataval);
+		g := ST_Intersection(geom, rast::geometry);
+		geomrast := ST_AsRaster(g, rast, ST_BandPixelType(rast, band), 1, newnodataval);
 
 		-- Compute the first raster band
 		newrast := ST_MapAlgebraExpr(rast, bandstart, geomrast, 1, '[rast1.val]', newpixtype, newextent, newnodataval::text, newnodataval::text, newnodataval);