[gdal-dev] Conformity of GeoPackage rasters generated by GDAL

[Even Rouault]

Hi,

Thanks to interoperability tests led by Brian Osborn from the sample GeoPackage with 
elevation data I generated, he spotted a more general issue with the registration of raster 
tiles that can cause spatial registration to be wrong when GDAL generated raster .gpkg are 
read by other implementations (to give full credit i think Brad Hards noticed this earlier)

I've fixed the issue in trunk and 2.1 branch per
https://trac.osgeo.org/gdal/ticket/6826

So if you need to ensure interoperability with other implementations, you'd better fetch the 
fix and regenerate your productions.

Note: You don't necessarilty need to regenerate the whole .gpkg, but you need to correct the 
content of gpkg_tile_matrix, so that for zoom_level = Z > 0 :
matrix_width(Z) = 2^Z * matrix_width(zoom_level=0)
matrix_height(Z) = 2^Z * matrix_height(zoom_level=0)

This is only when using no overview or power-of-two overviews. For non power-of-two 
overviews (which is an extension), I think there might be still issues.

Even

-- 
Spatialys - Geospatial professional services
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