#dsn <- dsn::vrtcon(sds::gebco(), ovr = 4)
dsn <- "vrt:///vsicurl/https://gebco2023.s3.valeria.science/gebco_2023_land_cog.tif?ovr=4"
scaled.vrt <- "scaled.vrt"
system(glue::glue("gdal_translate {dsn} scaled.vrt -scale -ot Byte"))
## here I had to edit the pal.vrt to have "scaled.vrt" rather than "mem" in the source (...)
system(glue::glue("gdalattachpct.py pal scaled.vrt pal.vrt -of VRT"))
## now we have to expand the palette to RGB/A (I don't think gdal_retile needs that)
system(glue::glue("gdal_translate pal.vrt rgb.vrt -expand rgb"))
unlink("tttfiles/", recursive = T)
dir.create("tttfiles")
system(glue::glue("gdal2tiles.py rgb.vrt tttfiles --tiledriver=PNG"))
