Hi, would you mind to write a smal FAQ for us? http://grass.osgeo.org/wiki/Faq
Thanks Markus On Fri, Apr 9, 2010 at 2:51 PM, Johannes Sommer <[email protected]> wrote: > David, > > thank you very much! I tested your approach with network isolines > derived from a dataset with one center - and it worked very well! > The automated approach will be interesting (also with more than one > center) - but therefore I need more experience in GRASS scripting. > > thanks, > Johannes > > David Mahoney schrieb: >> I went through this last year, and as I remember, v.hull doesn't quite >> get you there, since the resultant polygon can't "dip in" to reach >> concave sections of a service area. I used v.delaunay to create a >> network of the nodes that made up the connections between service areas, >> and v.net.salesman to generate the edges of the service areas. >> >> David >> >> On Mon, 2010-04-05 at 09:04 -0300, Daniel Victoria wrote: >> >>> If I understand you correctly, v.hull might help to create the service >>> area polygon from the points.... >>> >>> http://grass.itc.it/grass62/manuals/html62_user/v.hull.html >>> >>> On Sun, Apr 4, 2010 at 8:12 PM, Richard Chirgwin >>> <[email protected]> wrote: >>> >>>>> ------------------------------ >>>>> >>>>> Message: 3 >>>>> Date: Sat, 03 Apr 2010 23:11:26 +0200 >>>>> From: "Johannes Sommer" <[email protected]> >>>>> Subject: [GRASS-user] v.net.iso - service area >>>>> To: [email protected] >>>>> Message-ID: <[email protected]> >>>>> Content-Type: text/plain; charset="iso-8859-1" >>>>> >>>>> Hi list, >>>>> >>>>> recently I played around with the network functionality in ArcGIS. I >>>>> generated so called "Service Areas" in a network dataset which return the >>>>> regions that can be accessed in a network dataset based on several >>>>> distances >>>>> (in my example 150, 400 meters). >>>>> >>>>> I wanted to reproduce the results with GRASS GIS and after a short search >>>>> I found the module v.net.iso which seemed to fit my needs. It returns >>>>> exactly the same results as ArcGIS did on isolines on a network, but I >>>>> can't >>>>> find any solution concerning the service areas. >>>>> >>>>> Can anyone point me in the right direction to calculate zones (that is >>>>> "build polygons from the end points of each network segment") from these >>>>> generated isolines in a network? >>>>> >>>>> Regards, >>>>> >>>>> Johannes >>>>> >>>>> >>>>> >>>>> >>>> Johannes, >>>> >>>> I don't think there's anything to do this automatically in Grass-GIS. But I >>>> think you should be able to construct a script that would connect pairs of >>>> points. >>>> >>>> So if you can extract each end point of the network segment, you would end >>>> up with a vector containing only points - then create a temporary map of a >>>> point pair, run (say) v.distance output=connectors on each point pair, >>>> patch >>>> the resulting maps together ... >>>> >>>> It sounds a bit labourious, and probably someone else can think of >>>> something >>>> easier, but if you get all the individual steps right, a script is then >>>> easy >>>> to create. >>>> >>>> (Actually, Johannes, I think the idea is brilliant. I've done lots of >>>> network service area work, and it never occurred to me before!) >>>> >>>> Richard Chirgwin >>>> >>>> _______________________________________________ >>>> 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 > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
