Dear Helena, > I believe that any reasonable estimate is better than the current > shrinking region (in r.flow we just > propagate the same values to the edges), but that does not seem to be the > consensus.
I agree with you that a reasonable estimate is better than the current situation. I've opened an enhancement ticket for this (http://trac.osgeo.org/grass/ticket/2526). > you can use r.resamp.rst which computes slope and aspect and does not > shrink the region. But you may > need to adjust the parameters to make sure it works well. [...] > (you can compute the edge values e.g.in r.mapcalc). I'll have a look r.resamp.rst and r.mapcalc in the meantime. > I am quite interested in the flat valley bottoms. the authors [1] introduced a quite complex procedure to calculate an index of valley bottom flatness, but it seems to be used especially in soil science papers. I've used it a little bit for riverine landscape analysis. in r.valley.bottom [1] DEM coarsening and smoothing as suggested by Gallant & Dowling seems to work already; although a lot of code tweaking (especially to choose/calculate thresholds independently of base DEM resolution, ...) is still needed. testing and input is welcome. [1] "John C. Gallant and Trevor I. Dowling A multiresolution index of valley bottom flatness for mapping depositional areas. WATER RESOURCES RESEARCH, VOL. 39, NO. 12, 1347, doi:10.1029/2002WR001426, 2003" [2] http://trac.osgeo.org/grass/browser/grass-addons/grass7/raster/r.valley.bottom/r.valley.bottom.py ----- best regards Helmut -- View this message in context: http://osgeo-org.1560.x6.nabble.com/r-slope-aspect-one-pixel-less-in-the-output-at-the-border-shrinks-region-extent-in-further-calculatis-tp5179874p5179937.html Sent from the Grass - Dev mailing list archive at Nabble.com. _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
