[GRASS-user] Re: grass-user Digest, Vol 24, Issue 9: Problems with NVIZ Volume

GRASS GRASS user
1

Suenia:

I would assume that the setting of elevation of the location causes the trouble.

Maybe this will help you to set up the loaction properly:

Have a look at the code of r.in.srtm
(http://grass.itc.it/grass63/manuals/html63_user/r.in.srtm.html)
and/or consult the article by Markus Neteler about it in GRASS NEWS, VOl 3:
http://grass.itc.it/newsletter/GRASSNews_vol3.pdf

Cheers,
Peter

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Message: 1
Date: Tue, 8 Apr 2008 11:09:04 +0200 (CEST)
From: suenia <sueniii@yahoo.de>
Subject: [GRASS-user] Problems with NVIZ Volume (3dGRID) Visualization
  !
To: grass-user@lists.osgeo.org
Message-ID: <419470.5003.qm@web23212.mail.ird.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"

                Hello together !
  I have problems with NVIZ Volume visualization !
Here I made an example generating a simple 3dgrid volume assuming
subterranean data and the failing of visualizing it. I would really appreciate
some help !
      Here the short workflow:
#Generating three surfaces which will model the volume.
GRASS 6.2.2 (4326):~ > r.mapcalc dem.t=0
GRASS 6.2.2 (4326):~ > r.mapcalc dem.m=-10
GRASS 6.2.2 (4326):~ > r.mapcalc dem.b=-20
                          #My region settings
GRASS 6.2.2 (4326):~ > g.region -p3
projection: 3 (Latitude-Longitude)
zone: 0
datum: wgs84
ellipsoid: a=6378137 es=0.006694379990141316
north: 24:56:24N
south: 12:54S
west: 75:52:12E
east: 114:17:24E
top: 0.00000000
bottom: -20.00000000
nsres: 0:59:44.842105
nsres3: 0:59:44.842105
ewres: 1:00:39.789474
ewres3: 1:00:39.789474
tbres: 1
rows: 38
rows3: 38
cols: 38
cols3: 38
depths: 20
cells: 1444
3dcells: 28880

  #Generating the 3d grid volume
GRASS 6.2.2 (4326):~ > r.to.rast3 input=dem.b,dem.m,dem.t output=dem –o
    #Visualizing it!
GRASS 6.2.2 (4326):~ > nviz volume=dem elevation=dem.t

When visualizing the 3dgrid volume dem, together with the raster
surfaces, only outlines in form of a cube volume are drawn whenever navigating in
space !!! else nothing is seen but the raster surfaces.
  When adding a new constant value, for example -10, to the raster volume,
an associated unique colored surface at the bottom of the cube is
observable.
  So, I´m not sure about what could be the problem or my mistake in the
settings selection.
  Furthermore I would like to know how to change g.region res3,
respectivly tbres for latitude longitude locations, when I try to change
res3<0:59:44.842105 or tbres my region get's destroyed, definitely.
For what stands the default value 1 of tbres ?
  
Could somebody offer more information about vertical resolution
specifications for latitude longitude locations.
      That works : Slovakia3d can be visualised by adding new constant
value for the raster volume.

Many thanks !
Suena

--
Dr. Peter Löwe
<peter.loewe@gmx.de>

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