On jeudi 1 décembre 2016 11:45:43 CET Rahkonen Jukka (MML) wrote: > Hi, > > Let's say that I have these raster maps with 2048 m and 1024 m pixel sizes > http://kartat.kapsi.fi/files/taustakarttasarja_jhs180/taustakartta_8m/2048m/ > etrs89/png/Taustakartta_8milj.png > http://kartat.kapsi.fi/files/taustakarttasarja_jhs180/taustakartta_8m/2048m > /etrs89/png/Taustakartta_8milj.pgw > > http://kartat.kapsi.fi/files/taustakarttasarja_jhs180/taustakartta_4m/1024m/ > etrs89/png/Taustakartta_4milj.png > http://kartat.kapsi.fi/files/taustakarttasarja_jhs180/taustakartta_4m/1024m > /etrs89/png/Taustakartta_4milj.pgw > > Converting the 8milj.png into GeoPackage raster table is easy > > gdal_translate -of gpkg -a_srs epsg:3067 Taustakartta_8milj.png > overview.gpkg > > Image goes to zoom level 2 as reported by gdalinfo: > Metadata: > IDENTIFIER=overview > ZOOM_LEVEL=2 > > But now the hard part: I would like to append the second image 4milj.png to > the same layer "overview" as ZOOM_LEVEL=3 because that map is designed for > that resolution. Is it possible to do that by using some parameters of the > driver http://www.gdal.org/drv_geopackage_raster.html or with some clever > trick?
The following works: gdal_translate Taustakartta_4milj.png test.gpkg -of gpkg -a_srs epsg:3067 -expand rgba gdal_translate Taustakartta_8milj.png Taustakartta_8milj_rgba.tif -expand rgba gdalwarp Taustakartta_8milj_rgba.tif test.gpkg -doo ZOOM_LEVEL=2 Expension to RGBA wouldn't be strictly needed in theory since your 2 rasters have the same palette, but in practice you have to do it. Even -- Spatialys - Geospatial professional services http://www.spatialys.com
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