On Fri, Aug 26, 2016 at 9:56 AM, Micha Silver <[email protected]> wrote: > > > I also noticed that r.stream.extract finds different flow-paths than > r.watershed, which complicates comparisons between the two. The work-around > for this is to use a mask to force r.stream.extract to find the flow-path > you want. > > r.stream.extract is the preferred stream extraction tool. > > OK, but a flow accum raster is required for running r.stream.order (which > outputs flow_accum) and AFAIK, the only way to get a flow_accum raster is > with r.watershed. > ?? > > > BTW, I'm not the only one who has encountered this: > > http://gis.stackexchange.com/questions/201118/how-to-obtain-accumulation-map-from-r-stream-extract
The main purpose of r.stream.extract is to extract a stream network from any flow accumulation map and elevation map. The flow accumulation map can be produced with any other tool that is able to accumulate flow, and that tool does not need to be a GRASS module, e.g. TAUDEM output is also fine. Further on, any flow accumulation can be further processed before being used as input for r.stream.extract. For example, valleys identified by some curvature analysis could be enhanced. r.stream.extract can also work with only elevation as input. In this case flow accumulation is done internally similar to r.watershed. If you need flow accumulation, it must be calculated first and then used as input for r.stream.extract. Markus M > > Thanks, > > Best, > Micha > > > _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
