BD Ortho 5 m — aerial photography (reformatted)

The original files released by IGN on http://professionnels.ign.fr/bdortho-5m under Open License are: — in legal projection (Lambert 93 in metropolitan France and other specific projection for each DOM) — in JPEG2000 format “lossless” per slab of 10 km x 10 km — compressed as a 7z archive (long to be decompressed for marginal compression gain, with slabs already compressed) In order to make these aerial images more directly usable, for example on a website or an embedded application (an average department is 150 MB), the files proposed here are: — in projection Web Mercator (EPSG:3857) — in GeoPackage OGC format, with JPEG compressed content (quality 75) — each department is provided in a single standalone file, with no additional compression They are ultimately about 10 times less voluminous and more directly exploitable. ## Applied treatments They are made with [gdal](http://www.gdal.org) and the following parameters: “'” gdalwarp/tmp/$D.vrt $D.gpkg -t_srs EPSG:3857 -r cubic -of gpkg -overwrite -multi -cutline/tmp/$D.shp -crop_to_cutline -dstalpha gdaladdo $D.gpkg -r average --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW YCBCR --config INTERLEAVE_OVERVIEW PIXEL 4 16 64 “'”