Le vendredi 07 mars 2014 21:11:40, Even Rouault a écrit : > 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 :
I forgot to mention the "-co TILED=YES" which was actually used and makes a dramatic improvement for xpdf & QGIS use cases, compared to not tiling mode. > - 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 gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev