>> Maciek wrote > Carlos "Guâno" Grohmann wrote: >> Since nnbathy is cell-center oriented each >> N,S,E,W extent has to be shifted half a current GRASS region resolution >> to avoid it's output missalignment with current GRASS region.
> I always though that GRASS was cell-center oriented.. What do you mean? Explanation of why the shift in r.surf.nnbathy in necessary: The region: $ g.region -g n=404456 s=404453 w=315942 e=315945 nsres=1 ewres=1 rows=3 cols=3 cells=9 The input raster (* stands for null): 315942.5 404455.5 20 315943.5 404455.5 74 315944.5 404455.5 43 315942.5 404454.5 29 315943.5 404454.5 * 315944.5 404454.5 65 315942.5 404453.5 25 315943.5 404453.5 25 315944.5 404453.5 49 If the half-a-resolution shift IS applied (nnbathy -W 0 -P alg=nn -n 3x3 -x 315942.5 315944.5 -y 404455.5 404453.5), as described in previous post, the output of r.surf.nnbathy in=xxx out=yyy is alligned to the input raster: 315942.5 404455.5 20 315943.5 404455.5 74 315944.5 404455.5 43 315942.5 404454.5 29 315943.5 404454.5 48.25 315944.5 404454.5 65 315942.5 404453.5 25 315943.5 404453.5 25 315944.5 404453.5 49 If the shift IS NOT applied (nnbathy -W 0 -P alg=nn -n 3x3 -x 315942 315945 -y 404456 404453), the output is missaligned and interpolated wrong, due to nnbathy working region set wrong: 315942 404456 NaN 315943.5 404456 NaN 315945 404456 NaN 315942 404454.5 NaN 315943.5 404454.5 48.25 315945 404454.5 NaN 315942 404453 NaN 315943.5 404453 NaN 315945 404453 NaN Maciek _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
