Hi Chris, d.vect has an option to display the direction of lines, and the vector digitizer has a tool to flip the direction of things. The man pages have details about those things work.
Regards, Will On Wed, Mar 9, 2016 at 2:28 PM, Bartolomei.Chris <[email protected] > wrote: > Good afternoon, > I was hoping someone could provide some insight as to how v.net works. I > have a set of (438) watershed boundaries and their DEMs from which I have > created the stream vectors from the DEM rasters (r.watershed, r.thin, > r.to.vect, v.clean, etc.) I also have the set of USGS stream gauges as > points from which I extract the gauges within each watershed as a separate > map. I am able to use v.net op=connect to create a network with the > stream vectors and watershed gauge points no problem and v.path > successfully creates paths from one gauge to the next IF the forward and > backward costs are the same (cost is length). > What I am trying to do is measure the distance between a pair of gauges > that are in the same flow path. I am automating this so there is no user > input as to which pair to select, therefore I would like to use > v.net.allpairs and then analyze the resulting table and select only those > which have a route. > If I set the fwd cost to length and the backwards cost to -1 to shut off > going upstream after traversing downstream, then the paths fail – which in > many cases is good, but the paths between gauges that are clearly > up/downstream from each other (along the same flow path) fail as well. If I > reverse the forward and backward cost columns the path calculations still > fail. > My thoughts are that the stream vectors do not have the correct forward > and/or backward orientation (they are probably mixed) in the network. Is > there a way to see or set the orientation of the stream vectors? Does > anyone have experience with this? > When I created the stream vectors, I didn’t include the 3D data, if it > were included in the stream vector would the forward/backward orientation > then go from higher elevation to lower? > > I’ve looked at ( > https://grasswiki.osgeo.org/wiki/Vector_extract_upstream_network) and I > seem to lose a lot of (stream) lines when the network is created this way > which I feel may be related to the vector orientations as well. > > Any assistance would be greatly appreciated! > > Chris > > > > Chris Bartolomei P.E. > Engineer/Scientist > ENSCO, Inc. > 4849 North Wickham Road > Melbourne, FL 32940 (official office) > 5038 Park Rim Drive > San Diego, CA 92117 (home office) > (858) 581-3005 > [email protected] > > The information contained in this email message is intended only for the > use of the individual(s) to whom it is addressed and may contain > information that is privileged and sensitive. If you are not the intended > recipient, or otherwise have received this communication in error, please > notify the sender immediately by email at the above referenced address and > note that any further dissemination, distribution or copying of this > communication is strictly prohibited. > > The U.S. Export Control Laws regulate the export and re-export of > technology originating in the United States. This includes the electronic > transmission of information and software to foreign countries and to > certain foreign nationals. Recipient agrees to abide by these laws and > their regulations -- including the U.S. Department of Commerce Export > Administration Regulations and the U.S. Department of State International > Traffic in Arms Regulations -- and not to transfer, by electronic > transmission or otherwise, any content derived from this email to either a > foreign national or a foreign destination in violation of such laws. > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user
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