Le vendredi 07 mars 2014 14:20:13, Rahkonen Jukka (Tike) a écrit : > Hi Even, > > Yes, that way I can perhaps create an all-white PDF map a bit faster but > with no other improvement, unfortunately.
I've tried "gdal_translate UM5L.png UM5L.pdf -of pdf" on my Linux workstation and the the following viewers : - Adobe Reader 9.4.2 Linux: blank image - Okular, KDE-based PDF viewer, based on poppler library: can display a fit-to- page overview in a few seconds, but not the full resolution image since it tries to allocate a 15360x15360 buffer - Evince, GNOME-based PDF viewer, based on poppler library, uses cairo for display: blank image with error message "cairo context error: out of memory" - xpdf, viewer whose code has been forked to build the poppler library: can display the PDF at full resolution, and in reasonable time. - qgis (based on GDAL PDF driver, and poppler backend) : the initial overview computation is really really slow. Roughly half an hour. Because there's currently no optimization in the GDAL PDF reader to get a lower resolution image. Could potentially be dramatically improved by asking a rendering at lower DPI for overview levels, instead of querying at best DPI and then downsampling. But once that 32x32 overview is computed, if you go to 100% scale and pan, the refresh time is around 1 second after each pan. - command line "rendering" (based on GDAL PDF driver, and poppler backend) : gdal_translate UM5L_tiled.pdf out.tif -co TILED=YES : 1 minute 20 sec (less if you specify a higher value than the default for GDAL_CACHEMAX) I've also tried generating a JPEG2000 compressed PDF and Adore Reader is not happier. Conclusion: most PDF viewers assume that a PDF page can fit in memory and don't use a tiling strategy to display it. Even -- Geospatial professional services http://even.rouault.free.fr/services.html _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
