achim schrieb: > > achim schrieb: >> 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? > > -how can I distinguish between points and polylines? > to add a layer you can set a geometry type (eg. type=point) and do a > "v.category" (misleading name) in an additional layer > v.category --overwrite input=netw...@achim output=netw...@achim > type=point layer=2 > if you did it wrong before adding all geometries, you can delete > (option=del) some of the categories > v.category --overwrite input=netw...@achim output=netw...@achim > option=del type=line layer=2
be careful with overwriting! It deletes the tabe I think! > v.category --overwrite input=netw...@achim output=netw...@achim > option=del type=line layer=2 so first do v.category with overwriting and then add: v.db.addtable map=netw...@achim layer=1 v.db.addtable map=netw...@achim layer=2 here, it looks like one table with two layers, there are two tables: network network_2 (misleading again...but it works) > > (I feel a bit schizo) > > Questions remaining: > -> 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 > _______________________________________________ > 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
