PostGIS Raster : Extending PostgreSQL for The Support of ... - CoDE

SELECt rid, ST_UpperLeftX(rast)
FROM dummy_rast;
--Set the upper left corner coordinates of the raster whose rid number is 1
--from the table dummy_rast:
SELECT ST_SetUpperLeft(rast,-71.01,42.37)
FROM dummy_rast WHERE rid = 1;
• SRID and number of bands
–Get SRID of the raster whose rid is 1:
SELECT ST_SRID(rast) As srid
FROM dummy_rast WHERE rid=1;
–Set SRID of the raster whose rid is 1:
SELECT ST_SETSRID(rast) As newRast
FROM dummy_rast WHERE rid=1;
–Get number of bands of the raster whose rid is 1:
SELECT rid, ST_NumBands(rast)
FROM dummy_rast Where rid = 1;
• Get and set band properties –Pixel type and nodata value Get pixel type of band number 1 of
the raster whose rid is 1:
SELECT ST_BandPixelType(rast,1)
FROM dummy_rast
WHERE rid = 1;
Get no data value of band number 2 of the raster whose rid is 1:
SELECT ST_BandNoDataValue(rast,2)
FROM dummy_rast
WHERE rid = 1;
Set no data value of band number 2 of the raster, whose rid is 1, to 254:
UPDATE dummy_rast
SET rast = ST_SetBandNoDataValue(rast,2, 254)
WHERE rid = 1;
• Reproject rasters This operation will reproject the geographic locations of rasters into any appropriate
coordinate system for execution of some spatial operations. The reprojection is executed
using ST\_Transform(raster, srid, algorithm). This function uses specified resampling
algorithm such as NearestNeighbor, Bilinear, Cubic, CubicSpline or Lanczos. Default is NearestNeighbor.
The following query transforms all rasters of the dummy_rast table into WGS 84
(having the SRID number 4326) using Bilinear algorithm:
SELECT ST_Transform(rast,4326,’Bilinear’)
FROM dummy_rast ;
• Resample a raste Resample a raster with new dimensions, an arbitrary grid corner and a set of
raster georeferencing attributes. This operation is performed using ST_Resample(raster, width,
height, algorithm). New pixel values are computed using the NearestNeighbor, Bilinear, Cubic,
CubicSpline or Lanczos resampling algorithm. Default is NearestNeighbor.
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