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

GRASS GRASS user
1

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

Date: Thu, 28 Jan 2010 09:31:06 -0800 (PST)
From: Rich Shepard <rshepard@appl-ecosys.com>
Subject: [GRASS-user] r.param.scale Incorrect Output
To: grass-users@lists.osgeo.org
Message-ID:
       <alpine.LNX.2.00.1001280926180.23099@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