I am not totally sure, but I believe that the gdal data model always uses the upper left corner for the origin, even on files that reference the lower left in space. I think this is also the way rasterio handles it. See RasterIO docs:
http://gdal.org/classGDALDataset.html#e077c53268d2272eebed10b891a05743 Specifically the nXOff and nYOff parameters. kss # ============================ Kyle Shannon Physical Science Technician RMRS Fire Sciences Lab Fire, Fuels & Smoke - RWU 4405 5775 Highway 10 W. Missoula, MT 59808 (406)829-6954 kshan...@fs.fed.us # ============================ On Tue, Nov 16, 2010 at 5:28 PM, Todd Smith <smith.t...@gmail.com> wrote: > The default way of doing things at my company is to treat the lower left > corner of a file as the origin. Thus when I call RasterIO on a GeoTIFF, I > make the buffer I pass as pData address to the last row of the buffer I've > allocated, and I make nLineSpace negative. This has the effect of reading > the file from the beginning, but placing each line into my buffer starting > at the last and finishing at the first line. This was working great until I > started reading ArcInfo/Ascii files with origins in the lower-left. In this > case, I wouldn't want to address to the last row of my buffer, I'd want to > address to the beginning of my buffer, and use a positive value for my line > space. > > Is there metadata that will tell me where the file's origin is? If not, > any suggestions as to how to deal with this problem? > > Thanks! > > Todd > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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