Hi, I'm trying to follow/understand the calculation/algorithm of a multiresolution index of valley bottom flatness [1] transcribed to GRASS GIS.
"The remaining steps are similar to the second step. The main differences are that the DEM is smoothed, the resolution becomes coarser at each step, and the combined flatness from previous steps is included to prevent fine-scale nonflat areas being lost in the coarser-scale analysis." [...] First, a smoothed DEM (DEML,L,L-1) is derived without changing resolution. The smoothing is performed with the Arc/Info focal mean function using an 11 x 11 Gaussian smoothing kernel g(r) with an effective radius of three cells (to correspond with the factor of 3 resolution change): g(r) = 4.3565e -(r/3)2 [x to the power of n] where r is the distance (in cells) from the center of the kernel." [1] would there be r.resamp.filter [2] using a gauss filter the appropriate tool? maybe with?: r.resamp.filter radius= 3 Filter radius x_radius = 11 Filter radius (horizontal) y_radius= 11 Filter radius (vertical) ? but also in r.neighbors [3] there is a gauss option gauss=float Sigma (in cells) for Gaussian filter any hints/pointers? thanks Helmut [1] John C. Gallant and Trevor I. Dowling 2003. 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://grass.osgeo.org/grass71/manuals/r.resamp.filter.html [3] http://grass.osgeo.org/grass71/manuals/r.neighbors.html ----- best regards Helmut -- View this message in context: http://osgeo-org.1560.x6.nabble.com/r-resamp-filter-Resamples-raster-map-layers-using-an-analytic-kernel-how-to-use-gauss-filter-tp5143453.html Sent from the Grass - Dev mailing list archive at Nabble.com. _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev