ST_SetBandIsNoData — Sets the isnodata flag of the band to TRUE.
raster ST_SetBandIsNoData(raster rast, integer band=1);
Sets the isnodata flag for the band to true. Band 1 is assumed if not specified. This function should be called only when the flag is considered dirty. That is, when the result calling ST_BandIsNoData is different using TRUE as last argument and without using it
Availability: 2.0.0
This example creates a dummy table with one raster column. The raster has two bands and one pixel per band. In the first band, the NODATA value and pixel value are both 3. In the second band, the NODATA value is 13 and the pixel value is 4.
create table dummy_rast (rid integer, rast raster);
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)
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'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)
||
'0100' -- width (uint16 1)
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'0100' -- height (uint16 1)
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'4' -- hasnodatavalue set to true, isnodata value set to false (when it should be true)
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'2' -- first band type (4BUI)
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'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 false
select ST_BandIsNoData(rast, 1, TRUE) from dummy_rast where rid = 1; -- Expected true
The isnodata flag is dirty, so set
it to true.
update dummy_rast set rast = ST_SetBandIsNoData(rast, 1) where rid = 1;
select ST_BandIsNoData(rast, 1) from dummy_rast where rid = 1; -- Expected true