francesco wrote: > GRASS is great up the the million points limit, (2 Gb machine) > then things get problematic
hint: when importing as vector points with v.in.ascii you need to use the -b flag to avoid building topology. If you do that you can import as many points as you like without the RAM overhead. ..There is a small but finite memory overhead req'd for every feature with topology. After 2-3 million points that becomes an issue on a desktop with 2GB RAM. Also by default a simple x,y,z[,category integer] import will not create an attribute database. Add more (non-spatial) columns and by default it will create a DB. A database associated to your data via the category index is obviously some overhead too.. You can avoid building an associated attribute database with the v.in.ascii -t flag. This does mean unfortunately that if you have x,y,first hit,last hit,return strength,... data you'd have to import it as multiple maps, assigning the "z" to other meanings. On the plus side you can then use the d.vect module's -z flag to instantly colorize the rendering using any of the assortment of standard or custom color rules. You won't be able to do fancy stuff like network analysis without topology, but who uses that for points? when importing with r.in.xyz & piping from stdin, there is no limit to the size of import. (except for advanced methods like trimmed mean which eats RAM; not sure about skewness) When importing from a file you're limited by your OS/filesystem/ glibc. actually a 32 bit glibc might just break the percentage done status [ftell()], but the import would still work fine. And if you're starting from a file with random access ability you can switch on multi-pass import mode which means the RAM consuming trimmed mean (etc) can run in multiple passes, effectively avoiding the RAM problem. > Postgres/postgis is great for playing with complex queries but > what about visualization? no idea if they do, but if .vtk viewers like Paraview or VisIt had direct PostGIS support it would mean all sorts of awesomeness. http://www.paraview.org/paraview/project/imagegallery.php https://wci.llnl.gov/codes/visit/gallery.html regards, Hamish _______________________________________________ Liblas-devel mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/liblas-devel
