Using Python I have a program that makes a GeoTiff map by joining several maps and converting with rgb2pct.
This works perfect and when imported in QGIS georeferencing is OK. However, I want also GeoPDF (small size en sending to non experts). I use:
src_ds = gdal.Open(src)
driver = gdal.GetDriverByName("PDF")
dst_ds = driver.CreateCopy(dst, src_ds, 1)
This gives a GeoPDF also OK in QGis. The maps are 4000x5200 px. and should when printed at 20px/mm (508 dpi) print as exactly 1:25000 fitting on A4. I have tried a lot of options e.g.:
gdal.SetConfigOption("DPI", "4080")
gdal.SetConfigOption("WRITE_USERUNIT", "NO")
But to no avail.
How do I specify the correct dpi for the pdf. (pdfjam works perfect but geo info is lost)?