Michael Barton wrote: > > First, for a stream profile, you want to isolate a single watercourse. > r.stream.extract creates a stream network. Getting stream order does not > help with profiling, however. > > I looked at r.stream.distance. But this calculates distance from each stream > junction. I want it for the entire course of the selected stream—from > headwaters to outlet. That is the only way to graph a stream profile for the > entire stream.
You could use v.net + v.net.path to extract a single line from a given headwaters to a given outlet. r.stream.distance should then use the entire course of the selected stream. With a little loop this can be done for all streams of interest. Markus M > > Once I have a set of points with the distance from the beginning or the end > of the line stored as an attribute for each point, the rest is easy. It is > getting to this step that is hard. > > If a line is composed of multiple segments—as is the case for any line > created with r.stream.extract or r.watershed, and also with r.drain > surprisingly—there is nothing that will ignore all of these segments and > just give me the distance along the line from one end to the other. This is > the case with v.to.points and v.fixed.segmentpoints. v.profile might do the > job but it is not available for GRASS 7. > > Michael > > > > > > > > > > > On Nov 29, 2014, at 10:02 PM, grass-user-requ...@lists.osgeo.org wrote: > > From: César Augusto Ramírez Franco <caesar...@gmail.com> > To: GRASS User List <grass-user@lists.osgeo.org> > Date: November 29, 2014 at 9:13:43 PM MST > Subject: Re: [GRASS-user] how to change all cats in a vector line > > > Hello Michael > You could use r.stream.order after r.stream.extract to get your stream > network ordered, and then, after running r.thin on the ordered stream > network, convert it to vector using r.to.vect with the -v flag, that way, > each order is a cat, you can them use v.to.points or the add-on suggested > below to get topologically-correct points along the stream network, you > could also use r.stream.distance and upload distance and elevation to each > point using v.what.rast > I usually run R from within GRASS and use the spgrass6 library to read the > vector map and analyze the data there > Regards > César. > > El sáb, 29 de noviembre de 2014 06:29 p.m., Helmut Kudrnovsky > <hel...@web.de> escribió: >> >> Michael Barton wrote >> > Hi Markus, >> > >> > What I'm trying to do is start with a raster stream map from r.drain and >> > convert it to a sequence of vector points, where each point has >> > information as to its position along the stream. I then use the points >> > for >> > sampling a stream profile and related information. Oddly enough, with >> > all >> > of the very useful stream analysis modules, there is nothing I could >> > find >> > to generate the data for a stream profile (distance from outlet or from >> > headwaters vs. elevation). >> > >> > v.to.points does a nice job of creating a sequence of evenly spaced >> > points >> > with information about their location along a line (the "along" field). >> > BUT, if the line is composed of multiple segments or even if it has an >> > irregularity in it, the "along" values start over again from 0. The only >> > way I can use it is if I have a very clean and continuous vector line >> > with >> > only a single cat. >> > >> > This has proven surprisingly difficult to obtain reliably from my raster >> > stream map. So far, the only way has been to do a two sequences of >> > v.clean >> > (with thresholds 1.5 X the raster resolution) and v.build.polylines. If >> > you have any better suggestion, I'd love to hear it. >> > >> > Thanks again for the polylines idea. That was a big help. >> > >> > Michael >> > ____________________ >> > C. Michael Barton >> > Director, Center for Social Dynamics & Complexity >> > Professor of Anthropology, School of Human Evolution & Social Change >> > Head, Graduate Faculty in Complex Adaptive Systems Science >> > Arizona State University >> > >> > voice: 480-965-6262 (SHESC), 480-965-8130/727-9746 (CSDC) >> > fax: 480-965-7671 (SHESC), 480-727-0709 (CSDC) >> > www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu >> > > > > > _______________________________________________ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user