From: Regina Obe Date: Mon, 23 Jul 2012 00:46:14 +0000 (+0000) Subject: #1929 document behavior change and speed improvements X-Git-Tag: 2.1.0beta2~778 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=ea795c805eb0767614232f2bdeb0a1a5004eeb3a;p=postgis #1929 document behavior change and speed improvements git-svn-id: http://svn.osgeo.org/postgis/trunk@10086 b70326c6-7e19-0410-871a-916f4a2858ee --- diff --git a/doc/reference_raster.xml b/doc/reference_raster.xml index e4bc0b455..1f550af1b 100644 --- a/doc/reference_raster.xml +++ b/doc/reference_raster.xml @@ -7848,7 +7848,7 @@ SELECT ST_MapAlgebraFctNgb(rast, 1, '8BUI', 4,4, ST_Polygon - Returns a polygon geometry formed by the union of pixels that have a pixel value that is not no data value. If no band number is specified, band num defaults to 1. + Returns a multipolygon geometry formed by the union of pixels that have a pixel value that is not no data value. If no band number is specified, band num defaults to 1. @@ -7864,22 +7864,21 @@ SELECT ST_MapAlgebraFctNgb(rast, 1, '8BUI', 4,4, Description - Availability: Requires GDAL 1.7 or higher. + Availability: 0.1.6 Requires GDAL 1.7 or higher. + Enhanced: 2.1.0 Improved Speed (fully C-Based) + Changed: 2.1.0 In prior versions would sometimes return a polygon, changed to always return multipolygon Examples - --- by default no data band value is 0 or not set, so polygon will return a square polygon + -- by default no data band value is 0 or not set, so polygon will return a square polygon SELECT ST_AsText(ST_Polygon(rast)) As geomwkt FROM dummy_rast WHERE rid = 2; geomwkt -------------------------------------------- -POLYGON((3427927.8 5793243.75,3427927.75 5793243.75,3427927.75 5793243.8,3427927.75 5793243.85,3427927.75 5793243.9, -3427927.75 5793244,3427927.8 5793244,3427927.85 5793244,3427927.9 5793244,3427928 5793244,3427928 5793243.95, -3427928 5793243.85,3427928 5793243.8,3427928 5793243.75,3427927.85 5793243.75,3427927.8 5793243.75)) +MULTIPOLYGON(((3427927.75 5793244,3427928 5793244,3427928 5793243.75,3427927.75 5793243.75,3427927.75 5793244))) -- now we change the no data value of first band @@ -7895,10 +7894,7 @@ WHERE rid = 2; geomwkt --------------------------------------------------------- -MULTIPOLYGON(((3427927.9 5793243.95,3427927.85 5793243.95,3427927.85 5793244,3427927.9 5793244,3427927.9 5793243.95)), -((3427928 5793243.85,3427928 5793243.8,3427927.95 5793243.8,3427927.95 5793243.85,3427927.9 5793243.85,3427927.9 5793243.9,3427927.9 5793243.95,3427927.95 5793243.95,3427928 5793243.95,3427928 5793243.85)), -((3427927.8 5793243.75,3427927.75 5793243.75,3427927.75 5793243.8,3427927.75 5793243.85,3427927.75 5793243.9,3427927.75 5793244,3427927.8 5793244, -3427927.8 5793243.9,3427927.8 5793243.85,3427927.85 5793243.85,3427927.85 5793243.8,3427927.85 5793243.75,3427927.8 5793243.75))) +MULTIPOLYGON(((3427927.9 5793243.95,3427927.85 5793243.95,3427927.85 5793244,3427927.9 5793244,3427927.9 5793243.95)),((3427928 5793243.85,3427928 5793243.8,3427927.95 5793243.8,3427927.95 5793243.85,3427927.9 5793243.85,3427927.9 5793243.9,3427927.9 5793243.95,3427927.95 5793243.95,3427928 5793243.95,3427928 5793243.85)),((3427927.8 5793243.75,3427927.75 5793243.75,3427927.75 5793243.8,3427927.75 5793243.85,3427927.75 5793243.9,3427927.75 5793244,3427927.8 5793244,3427927.8 5793243.9,3427927.8 5793243.85,3427927.85 5793243.85,3427927.85 5793243.8,3427927.85 5793243.75,3427927.8 5793243.75))) -- Or if you want the no data value different for just one time @@ -7912,11 +7908,7 @@ WHERE rid =2; geomwkt --------------------------------- -POLYGON((3427928 5793243.85,3427928 5793243.8,3427928 5793243.75,3427927.85 5793243.75,3427927.8 5793243.75,3427927.8 5793243.8,3427927.75 5793243.8,3427927.75 5793243.85,3427927.75 5793243.9,3427927.75 5793244,3427927.8 5793244,3427927.85 5793244,3427927.9 5793244,3427928 5793244,3427928 5793243.95,3427928 5793243.85), -(3427927.9 5793243.9,3427927.9 5793243.85,3427927.95 5793243.85,3427927.95 5793243.9,3427927.9 5793243.9)) - - - +MULTIPOLYGON(((3427928 5793243.85,3427928 5793243.8,3427928 5793243.75,3427927.85 5793243.75,3427927.8 5793243.75,3427927.8 5793243.8,3427927.75 5793243.8,3427927.75 5793243.85,3427927.75 5793243.9,3427927.75 5793244,3427927.8 5793244,3427927.85 5793244,3427927.9 5793244,3427928 5793244,3427928 5793243.95,3427928 5793243.85),(3427927.9 5793243.9,3427927.9 5793243.85,3427927.95 5793243.85,3427927.95 5793243.9,3427927.9 5793243.9))) See Also