Dear readers, Is this the right place to post some questions and suggestions for improvements? I respond to the remark about the v.rast.stats option, I totally agree with the lack of speed problem. I had to perform the operation on 3,000,000+ polygons on a 33,000 * 28,000 raster... impossible. Also too much for ArcGIS, the only one that came through was gvSIG, and stunningly fast, in a little over an hour.
I'm experimenting with the new 6.4RC3 version, to check whether Grass could replace ArcINFO in certain research groups within our institute. To avoid problems with hardware resources I work with both an Intel Mac Core 2 Duo 2.4GHz with 4GB of RAM, as well as with a Pentium D Dual Core 3.0GHz with 4GB of RAM, so I'm at least prepared for heavy tasks. Generally spoken I run into problems when dealing with extremely large datasets. Besides the previous problem I ran into the following: -topology cleaning on large vector files (see bug report 494 on trac) -tried to save a subselect of 1000 polygons/areas from a 1,500,000+ dataset using v.extract, and stopped the operation after an hour or so, the new vector data file gets created quite quickly, but it looks to me as if the problem is in the database or data extraction -deleting a vector dataset must be done manually when for some reason the database link cannot be found, which is sometime very annoying, the force option should delete it anyway -using the python gui, selecting a very large vector file from a dropdown box (e.g. to show it in a map) takes a lot of time (it starts v.category, shouldn't do so) Other weird problems I noted: -using the old tcltk gui the map display doesn't update when loading multiple datasets, is this specific to my mega-datasets again? -the classic d.what.rast on an x monitor (d.mon ) does not work on my mega raster Apart from this, I created a simple enhancement in the form of a shell script, which automatically generates a new database schema when creating a new mapset, and you're already logged in into a PostgreSQL database. This makes it easy to create new mapsets connected to PostgreSQL, after having initially set up a PostgreSQL database + permanent schema. Maybe this should be integrated into the g.mapset command. This is about it so far. I actually like Grass, it's not the most 'open' software to work with from a users perspective, but it's powerful, and the new gui is certainly promising, also for less experienced users! Only ultra-large dataset support and some very slow vector operations should really be tuned up. And I love the command-line, don't drop it in favour of gui's. I hope you can do something useful with this information. Kind regards, Wouter _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
