PostGIS
Synopsis
boolean +`*`+ST_BandIsNoData*(`raster `rast, integer band,
boolean forceChecking=true`)`;
boolean +`*`+ST_BandIsNoData*(`raster `rast, boolean
forceChecking=true`)`;
Description
Returns true if the band is filled with only nodata values. Band 1 is assumed if not specified. If the last argument is TRUE, the entire band is checked pixel by pixel. Otherwise, the function simply returns the value of the isnodata flag for the band. The default value for this parameter is FALSE, if not specified.
Availability: 2.0.0
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Examples
-- Create dummy table with one raster column
create table dummy_rast (rid integer, rast raster);
-- Add raster with two bands, one pixel/band. In the first band, nodatavalue = pixel value = 3.
-- In the second band, nodatavalue = 13, pixel value = 4
insert into dummy_rast values(1,
(
'01' -- little endian (uint8 ndr)
||
'0000' -- version (uint16 0)
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'0200' -- nBands (uint16 0)
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'17263529ED684A3F' -- scaleX (float64 0.000805965234044584)
||
'F9253529ED684ABF' -- scaleY (float64 -0.00080596523404458)
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'1C9F33CE69E352C0' -- ipX (float64 -75.5533328537098)
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'718F0E9A27A44840' -- ipY (float64 49.2824585505576)
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'ED50EB853EC32B3F' -- skewX (float64 0.000211812383858707)
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'7550EB853EC32B3F' -- skewY (float64 0.000211812383858704)
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'E6100000' -- SRID (int32 4326)
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'0100' -- width (uint16 1)
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'0100' -- height (uint16 1)
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'6' -- hasnodatavalue and isnodata value set to true.
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'2' -- first band type (4BUI)
||
'03' -- novalue==3
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'03' -- pixel(0,0)==3 (same that nodata)
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'0' -- hasnodatavalue set to false
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'5' -- second band type (16BSI)
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'0D00' -- novalue==13
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'0400' -- pixel(0,0)==4
)::raster
);
select st_bandisnodata(rast, 1) from dummy_rast where rid = 1; -- Expected true
select st_bandisnodata(rast, 2) from dummy_rast where rid = 1; -- Expected false