Il 19:52, giovedì 22 marzo 2007, Armin Burger ha scritto: > Alessandro Pasotti wrote: > > Some technical info: > > > > Raster map is 1.5GB GEOTIFF with internal tiles and overviews > > Resource and itineraries vectors are in POSTGIS tables, the latter being > > an arc<->node M2M network > > Other vectors are in shapefile format, some of them are quite heavy: > > level curves are over 700MB. > > > > Hardware is double XEON 3GHz with 4GB RAM and SCSI disk. > > > > Performaces are lower than I expected, this is mainly due to the huge > > raster and POSTGIS vectors being slow despite proper indexing. This is > > the reason why most layers are off by default. > > One reason for bad performance could be the use of Mapserver 4.10. At > least with huge imagery and output as Jpeg it can take much more time > than with MS 4.8. I discovered that recently, but I had no time to > further investigate in that.
Thanks Armin, I find the discussions about performance optimization very interesting and every suggestion is welcome. The output is PNG24 (RGB) so maybe this is not the issue, or mapserver 4.10 is also slower on PNG? > > 1.5 GB Tiff is not very much for imagery, satellite datasets often have > up to 2 GB for single files. With overviews they are displayed very > efficiently. A problem could just be if the images are split up into > lots of small files. Then it helps to merge them into bigger chunks of > up to a few 100's MB each. It is one single GEOTIFF 24bit file with internal overviews an tiles. > > The display of contour lines can be very slow if you have some lines > that are extremely 'long'. They need to be read completely even if just > some parts are displayed. For that it helps splitting the lines into > smaller chunks, e.g. with an intersection applied to it using a regular > polygon grid as overlay. This is probably one of the main reasons, I will try splitting the curves. > > The only time I found PostGIS data very slow was when I defined the > re-projection in the data tag for PostGIS, thus letting PostGIS do the > projection transformation. Re-projection inside Mapserver was up to 10 > times faster. Not my case, projection is homogeneous so no need for reprojection. -- Alessandro Pasotti itOpen - "Open Solutions for the Net Age" w3: www.itopen.it Linux User# 167502 ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ pmapper-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/pmapper-users
