Database Reference
In-Depth Information
A netCDF dataset is composed of multiple subdatasets; each subdataset is com-
posed of multiple raster bands. Each band is composed of cells. This structure
shouldbecleartoyouafterinvestigatingasamplenetCDFdatasetusingthe
gdal-
info
GDAL command tool.
There are several approaches to export the cell values to PostGIS. The approach
youadoptedhereistogenerateaPostGISPointlayerforeachsubdataset,whichis
composed of one field for each subdataset band. You then iterated the raster cells
andappendedapointtothePostGISlayerwiththevaluesreadfromeachcellband.
ThewayyoudothiswithPythonisbyusingtheGDALPythonbindings.Forreading,
youopenthenetCDFdatasetandforupdating,youopenthePostGISdatabaseus-
ingthecorrectGDALandOGRdrivers.ThenyouiteratethenetCDFsubdatasetsus-
ingthe
GetSubDatasets
methodandcreateforeachsubdatasetaPostGIStable
namedasthenetCDFsubdatasetvariable(withtheprefix)usingthe
CreateLayer
method.
Foreachsubdataset,youiterateitsbandsusingthe
GetRasterBand
method.For
readingeachband,yourunthe
ReadAsArray
methodthatusesNumpytogetthe
band as an array.
Foreachband,youcreateafieldinthePostGISlayerwiththecorrectfielddatatype
thatwillbeabletostoretheband'svalues.Tochoosethecorrectdatatype,youin-
vestigate the band's data type usingthe
DataType
property.
Finally,youiteratetherastercells,byreadingthecorrect
x
and
y
coordinatesusing
thesubdatasettransformparameters,availableviathe
GetGeoTransform
method.
For each cell, you create a point with the
CreateGeometryFromWkt
method and
then set the fields values, read from the band array, using the
SetField
feature
method.
Finally,youappendthenewpointtothePostGISlayerusingthe
CreateFeature
method.
