achim schrieb: > Hi, > > I am going to do some work on drainage networks I created. I could not > figure out some basic procedures. Maybe, you have some ideas how to work > with some of the following questions/tasks: > > 1) how is a network stored? creating it via v.net from a multiline "map" > says it wants to create two layers: one with lines, the other with points > -> general problem: creating an table containing an entry for every > object (Id). I know thats general, but why doesn't it work with > v.db.newtable? And why answers v.to.db option=cat with > "Reading features... Updating database... 0 categories read from vector > map (layer 1) 0 records updated/inserted (layer 1)"?
to 1) make sure, the map is connected to the desired database. if necessary overwrite current connection and delete tables -> db.droptable -f table=network -> v.db.connect -d map=netw...@achim then do a -> v.db.addtable map=netw...@achim layer=1 all geometry objects get a number (maybe a v.category is necessary before) -> Questions remaining: -how can I distinguish between points and polylines? -how are connections (polyline)-node-(polyline/polyline) stored/defined? > 2) how can I identify each network by eg. an integer value? There are > many unconnected trees, which I want to keep separated. > -> I tried it with v.buffer, on the one hand I couldn't upload the > information to the network (points and polylines) and on the other hand > it takes a lot of time. > > 3) can I define a "direction" of a network with values on the nodes? > like a sorted tree? in order to get the sub trees? > > 4) how can I find out, which and how many lines are connected to a node? > > 5) ...there are some, but I think its enough; and furthermore the > questions more or less depend on each other. > > Hoping, someone has some experience with that kind of stuff, > kindly regards, > Achim > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
