[gdal-dev] Re: Fwd: Shift of geoTiff
ben at malleefocus.com.au
Tue Jun 8 23:36:58 EDT 2010
(Ben here - thought I'd have a look at this list)...
Jukka that looks right if the origin is the upper left corner of the upper
According to the GeoTiff spec
would be the 'PixelIsArea' raster grid space - which is the default (see
There is a PixelIsPoint raster grid space (also defined in 126.96.36.199), which
has the origin at the centre of the upper left pixel. In that case (cols -
1) x dx and (rows-1) x dy are right for getting the corner coordinates,
which are the centres and not the extremities of pixels. I have a feeling
the GeoTIFF I sent Paul is one of these types, because the MetaData supplied
with the file implies it. In the MetaData the corner coordinates given are
(cols-1) x dx and (rows-1) x dy away from eachother.
GDALINFO is reporting (AREA_OR_POINT) that the GeoTIFF is a 'Point' type,
which means that it is GDAL that is not rendering the coordinates correctly,
and not a problem with the GeoTIFF.
The GeoTIFFs, by the way, are produced by USGS from Landsat 4, 5 and 7 data
and distributed worldwide, freely, through http://glovis.usgs.gov/. There
will be plenty of people who are half a pixel out! SAGA (and presumably
other GDAL-based GIS) has the same problem with these GeoTIFFs.
Thank you for looking into it
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