On Tue, Sep 20, 2016 at 10:53 AM, Mira Kattwinkel <[email protected]> wrote: > Dear List > > r.stream.order gives, among other output, the distance of current the stream > init from the outlet of the catchment ('out_dist'). So for the most > downstream segment this is identical to the length of the segment. > r.stream.distance calculates the distance to the outlet and results in a > raster file. Both are based on a stream raster and a direction raster. > > When I compare the results, they are slightly different, although based on > the same input files (see the attached Fig1). The raster value is 212.33 at > the junction, while the out_dist of the line is 237.69. The difference is > one cellsize (25.023 in may example), probably due to the horizontal bit of > the line at the end (upper right of the figure).
Yes, this horizontal bit of the line is a bug in r.stream.order, the stream vector is leaving the current region or going into a NULL cell. All other r.stream.* modules place the outlet on a valid cell. Fixed in r69542. > However, this difference is > not fixed. In the middle of the network (Fig2) it is larger (81028.9 - > 81002.89 = 27). What is the difference in the middle of the network now with r69542? Markus M > > What is the reason for this difference? Is this a bug or a wanted behaviour? > > I want to extract the position of points on the network (i.e. upstream of a > junction on the lines). To this end, I planned to use the upstream distance > of the points and the out_dist of the segments (length(segment) - > (out_dist(segment) - upDist(point)) = position(point)). > Has anybody another idea how to accomplish this? > > Thanks a lot, > Mira > > > _______________________________________________ > 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
