[GRASS-user] r.param.scale Incorrect Output

[Michael Barton]

On Jan 28, 2010, at 10:31 AM, grass-user-request at lists.osgeo.org wrote:

> Date: Thu, 28 Jan 2010 09:31:06 -0800 (PST)
> From: Rich Shepard <rshepard at appl-ecosys.com>
> Subject: [GRASS-user] r.param.scale Incorrect Output
> To: grass-users at lists.osgeo.org
> Message-ID:
>        <alpine.LNX.2.00.1001280926180.23099 at salmo.appl-ecosys.com>
> Content-Type: text/plain; charset="us-ascii"
> 
>   I'm stymied trying to get output from r.param.scale that is equivalent to
> the example on the bottom of the man page.
> 
>   1) GRASS 6.4.0svn (Oregon):/usr4/grassbase > g.region rast=aberDEM res=10
> -ap
> projection: 99 (Lambert Conformal Conic)
> zone:       0
> datum:      nad83
> ellipsoid:  grs80
> north:      1334420
> south:      1279150
> west:       769190
> east:       819260
> nsres:      10
> ewres:      10
> rows:       5527
> cols:       5007
> cells:      27673689
> 
>   This sets the region to the input DEM map at 10m resolution.
> 
>   2) GRASS 6.4.0svn (Oregon):/usr4/grassbase > r.param.scale in=aberDEM
> out=morphology param=feature size=9 --o
>  100%
> 
>   No complaints. However, when I view the results using
> 
>   3) d.mon x0
>      d.rast.leg morphology
> 
> the results are shown in the attached screenshot (shrunk to keep the file
> size small).
> 
>   What might cause such output?

The difference is due to your resolution. Vary the resolution (computational region, not display region) and your moving window size to get the results you want. Bigger moving windows and lower resolutions will produce larger features.

Michael