[gdal-dev] Generating Cloud Optimized GeoTIFFs
even.rouault at spatialys.com
Tue Aug 29 09:45:21 PDT 2017
On mardi 29 août 2017 09:27:33 CEST daunnc wrote:
> Hi everybody! We're implementing COGs support in GeoTrellis, and there is
> appeared a question related to cloud optimized geotiff definition.
> Following this <https://trac.osgeo.org/gdal/wiki/CloudOptimizedGeoTIFF>
> // in.tif is some random tiff.
> 1. gdaladdo in.tif 2 4 8 16 32
> 2. gdal_translate in.tif out.tif -co TILED=YES -co COPY_SRC_OVERVIEWS=YES
> -co COMPRESS=DEFLATE
> After that using this
> hasacloudoptimizationinternalorganization> python script decided to validate
> the result and was confused by missing IFD_OFFSET tag.
confused ? Can you report the exact error ?
IFD_OFFSET should always be reported for any (valid) TIFF, be it COG or not. This is the offset
in the file of the image directory, and we must check that it is right at the beginning of the
file for efficient reading.
I suspect some issue with your setup, although I'm not clear which one. I'd have said perhaps
you'd run the script against an older GDAL version, but the script does version checking..
To debug this you could try setting a breakpoint in GTiffRasterBand::GetMetadataItem and
check what happens.
> Can BigTiffs be cloud optimized and can / should BigTiff
> have an offset == 8 as well (16 is a usual offset for them)?
You're absolutely right. I've just fixed the script to accept those.
Spatialys - Geospatial professional services
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