[gdal-dev] NetCDF geotransform - pixel centre/upper-left issue

Pinner, Luke Luke.Pinner at environment.gov.au
Tue Apr 6 01:32:26 EDT 2010

The NetCDF driver computes the pixel centre from lat/lon variables (see

Is this correct or should it compute pixel upper-left?

Using the example NetCDF dataset attached to the above ticket
(http://trac.osgeo.org/gdal/attachment/ticket/1506/out.nc), gdalinfo
reports the min longitude value to be -1.40625 which is not a valid
longitude (it's 1/2 a pixel less than 0 which is the min value in the
NetCDF lon variable).

gdalinfo out.nc
$ gdalinfo -nomd out.nc
Warning 1: Latitude grid not spaced evenly.
Seting projection for grid spacing is within 0.1 degrees threshold.

Driver: netCDF/Network Common Data Format
Files: out.nc
Size is 128, 64
Coordinate System is `'
Origin = (-1.406250000000000,89.258462312871046)
Pixel Size = (2.812500000000000,-2.789326947277220)
Corner Coordinates:
Upper Left  (  -1.4062500,  89.2584623) 
Lower Left  (  -1.4062500, -89.2584623) 
Upper Right (     358.594,      89.258) 
Lower Right (     358.594,     -89.258) 
Center      ( 178.5937500,   0.0000000) 
Band 1 Block=128x1 Type=Float32, ColorInterp=Undefined
  NoData Value=9.96920996838686905e+36


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