stephen sefick wrote: > When you reproject a raster map to a new location does it > automatically re-sample it to the regions resolution. I have a 10x10 > meter grid in albers equal area projection. I have reprojected it > into UTM zone 17 res=50. This is a base flow index map bfi. Does > grass resample the map to 50x50m?
Yes, given that the _target_ location is of res=50. You can, however, control this by changing the resolution (g.region) or directly at the reprojection process by setting the "resolution=" parameter of the "r.proj" module. You can even set the resampling algorithm (default nearest neighbour or bilinear). Hope this is what you've been looking for. Nikos > The problem is this: > I have an average runoff value (arv) in m/s (converted from mm/day > into m/s by dividing by 86,400s*1000mm). > flow accumulation grid produced by r.terraflow (which was 30x30m > resampled to 50x50m). > flow accumulation * 250 (to get square meters (50x50)) > > bfi*arv*flow accumulation (sqm) > > to get discharge in cms > > I converted this to cfs (multiplied by 35.314454) > > the resulting map is discharge in cfs > > The estimate for discharge is ~3x what the long term average is at > usgs gauging stations along the rivers of interest (point layer to > identify where they are located). The only thing that I have been > able to think of at this point is that there is a resampling step I am > missing because 10x10=100 and 50x50=250. which would account for > almost the 3x discrepancy. > > If you need anymore information please don't hesitate to ask. I > appreciate any and all help. _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
