I want to delete the orthoimage from a downloaded USGS geo.pdf so that I only have the topo. I run the following command
C:\OSGeo4W>gdal_translate "C:\Users\...\Blacksburg_geo.pdf" --config GDAL_PDF_LAYERS_OFF "Image" "C\Users\...\Blacksburg.pdf" It strips the orthoimage as desired, but renders a very poor quality topo map image. I'm not aware of any options to improve image quality.
gdal_translate is rasterizing the output, you can increase the quality of the raster output by increasing the DPI with a config or open option
--config GDAL_PDF_DPI=300 or
-oo DPI=300 E.g:
gdal_translate --config GDAL_PDF_DPI=300 --config GDAL_PDF_LAYERS_OFF "Image" Blacksburg_geo.pdf Blacksburg.pdf Default resolution:
300 DPI:
A couple of alternatives:
you can retain vector layers with ogr2ogr but you'll get much worse quality visually as the marginalia, symbology and drawing order gets messed up.
you can (depending on your PDF viewer) just open the layers side panel and turn the ortho off in the original PDF so it doesn't display, e.g:
