[gdal-dev] Geopackage raster and COPY_SRC_OVERVIEWS
even.rouault at spatialys.com
Mon Aug 28 05:02:34 PDT 2017
On lundi 28 août 2017 11:30:00 CEST Rahkonen Jukka (MML) wrote:
> I wonder if it could be feasible to support similar COPY_SRC_OVERVIEWS
> option than GeoTIFF driver does for existing overview levels which match
> with the power of two series. Some people have constructed GeoTIFFs or
> virtual VRT rasters which have overviews from different raster sources
> (raster maps with different rendering according to the scale) and gdaladdo
> can't generate such overviews from the best resolution level.
That's certainly doable (pending someone actually implementing it) and probably something
that could be generalized at the gdal_translate level
In the meantime, you can achieve a similar result with for example gdalwarp (in update
mode) and using the GPKG ZOOM_LEVEL open option.
- gdal_translate small_world.tif small_world.gpkg -of gpkg
(the full resolution data is at zoom level 1)
- gdal_translate small_world.tif ovr.tif -outsize 50% 50% -scale 0 255 127 255
(create a brighter overview)
- gdalwarp ovr.tif small_world.gpkg -doo ZOOM_LEVEL=0
(populate zoom_level=0, ie first overview level, with the content of this file)
The above can be generalized too as many overviews as needed. You may need to use the -
ovr switch of gdalwarp to select the appropriate source overview.
Spatialys - Geospatial professional services
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