Changes between Version 78 and Version 79 of WKTRaster/SpecificationWorking03

Timestamp:

05/16/11 11:22:48 (14 years ago)

Author:

dustymugs

Comment:

Updated ST_MinMax

WKTRaster/SpecificationWorking03

@@ -647 +647 @@
 
 '''ST_MinMax(raster, nband) -> record'''[[BR]]
-As part of the process to provide complete implementations of ST_AsJPEG and ST_AsPNG, a method is required to reclassify larger numbers unable to be contained in 8BUI (JPEG and PNG) and 16BUI (PNG). For this reclassification function, we need to get the min and max values of a band, thus ST_MinMax.  This function calls upon ST_SummaryStats.
+This function calls ST_SummaryStats and only returns the min and max values from that function.
 
 1. ST_MinMax(rast raster, nband int, hasnodata boolean) -> record
 
-  returns one record of two columns (min, max)
-
-  nband: index of band to process on
-
-  hasnodata: if FALSE, any pixel who's value is nodata is ignored.
-
-{{{
-ST_MinMax(rast, 2, TRUE)
+  returns the record (min double precision, max double precision)
+
+  nband: index of band
+
+  hasnodata: if FALSE, any pixel who's value is nodata is ignored
+
+{{{
+ST_MinMax(rast, 1, FALSE)
 }}}
 
@@ -671 +671 @@
 3. ST_MinMax(rast raster, hasnodata boolean) -> record
 
-  assumes band index = 1
-
-{{{
-ST_MinMax(rast, FALSE)
+  assumes nband = 1
+
+{{{
+ST_MinMax(rast, TRUE)
 }}}
 
 4. ST_MinMax(rast raster) -> record
 
-  assumes band index = 1 and hasnodata = FALSE
+  assumes nband = 1 and hasnodata = FALSE
 
 {{{
@@ -685 +685 @@
 }}}
 
-The ST_ApproxMinMax functions are:
-
-1. ST_ApproxMinMax(rast raster, nband int, hasnodata boolean, sample_percent double precision) -> record
-
-  sample_percent: a value between 0 and 1 indicating the percentage of the raster band's pixels to consider when determining the min/max pair.
+The set of ST_ApproxMinMax functions are:
+
+1. ST_ApproxMinMax(rast raster, nband int, hasnodata boolean, sample_percent record) -> record
+
+  sample_percent: a value between 0 and 1 indicating the percentage of the raster band's pixels to consider
 
 {{{
@@ -733 +733 @@
 }}}
 
-----
+The following functions are provided for coverage tables.
+
+1. ST_MinMax(rastertable text, rastercolumn text, nband int, hasnodata boolean) -> record
+
+  rastertable: name of table with raster column
+
+  rastercolumn: name of column of data type raster
+
+{{{
+ST_MinMax('tmax_2010', 'rast', 1, FALSE)
+
+ST_MinMax('precip_2011', 'rast', 1, TRUE)
+}}}
+
+2. ST_MinMax(rastertable text, rastercolumn text, nband int) -> record
+
+    hasnodata = FALSE
+
+{{{
+ST_MinMax('tmax_2010', 'rast', 1)
+}}}
+
+3. ST_MinMax(rastertable text, rastercolumn text, hasnodata boolean) -> record
+
+    nband = 1
+
+{{{
+ST_MinMax('precip_2011', 'rast', TRUE)
+}}}
+
+4. ST_MinMax(rastertable text, rastercolumn text) -> record
+
+    nband = 1 and hasnodata = FALSE
+
+{{{
+ST_MinMax('tmin_2009', 'rast')
+}}}
+
+Variations for ST_ApproxMinMax are:
+
+1. ST_ApproxMinMax(rastertable text, rastercolumn text, nband int, hasnodata boolean, sample_percent double precision) -> record
+
+{{{
+ST_ApproxMinMax('tmax_2010', 'rast', 1, FALSE, 0.5)
+
+ST_ApproxMinMax('precip_2011', 'rast', 1, TRUE, 0.2)
+}}}
+
+2. ST_ApproxMinMax(rastertable text, rastercolumn text, nband int, sample_percent double precision) -> record
+
+    hasnodata = FALSE
+
+{{{
+ST_ApproxMinMax('tmax_2010', 'rast', 1, 0.5)
+
+ST_ApproxMinMax('precip_2011', 'rast', 1, 0.2)
+}}}
+
+3. ST_ApproxMinMax(rastertable text, rastercolumn text, hasnodata boolean, sample_percent double precision) -> record
+
+    nband = 1
+
+{{{
+ST_ApproxMinMax('tmax_2010', 'rast', FALSE, 0.5)
+
+ST_ApproxMinMax('precip_2011', 'rast', TRUE, 0.2)
+}}}
+
+4. ST_ApproxMinMax(rastertable text, rastercolumn text, sample_percent double precision) -> record
+
+    nband = 1 and hasnodata = FALSE
+
+{{{
+ST_ApproxMinMax('tmax_2010', 'rast', 0.5)
+
+ST_ApproxMinMax('precip_2011', 'rast', 0.2)
+}}}
+
+5. ST_ApproxMinMax(rastertable text, rastercolumn text) -> record
+
+    nband = 1, hasnodata = FALSE and sample_percent = 0.1
+
+{{{
+ST_ApproxMinMax('tmax_2010', 'rast')
+
+ST_ApproxMinMax('precip_2011', 'rast')
+}}}
+
+----
+
 '''ST_AsJPEG(raster, quality) -> JPEG as "bytea"'''[[BR]]
 Return the raster as a JPEG encoded as a PostgreSQL bytea. By default quality is set to 75, but this option can be used to select other values. Values must be in the range 10-100. Low values result in higher compression ratios, but poorer image quality. Values above 95 are not meaningfully better quality but can but substantially larger. (copied from http://www.gdal.org/frmt_jpeg.html)