[GRASS-user] Generate 3D raster from two surfaces

[grass at sundquist.imapmail.org]

I admit I am not a pro (but I have devoured both the 2nd and 3rd
editions of "the book", and have been using GRASS on and of for about 5
years now), but I am lost on this command.

Here is part of what I am trying to do:  Let's try showing just a 3D
raster of the space between the ground surface and the bottom (I have a
few otehr more intersting applications, too, but this is the simplest).  

I put GTiff exports of these files here:
http://public.sundquist.imapmail.org/bottom_2.tif and
http://public.sundquist.imapmail.org/ground_surface.tif 

I want to generate a 3D raster showing the space between these two
surfaces.

I tried running this command:

 r.to.rast3elev input=ground_surface,AREA_DSM
 elevation=ground_surface,AREA_DSM output=3d1

and got no errors but got essentially nothing:

r3.univar input=3d1 at PERMANENT                                            
total null and non-null cells: 546
total null cells: 469
Of the non-null cells:
----------------------
n: 77
minimum: 1
maximum: 1
range: 0
mean: 1
mean of absolute values: 1
standard deviation: 0
variance: 0
variation coefficient: 0 %
sum: 77

I added to input files because when I tried just one, it said the number
of input and elevation files must match.  Note, I do not care about the
actual values in the 3D raster, just whether they are null or not.

Sorry if this is a basic question, but if I can get this generated, it
would be very helpful for explaining something to a client.

Thanks.

J.S.

On Mon, 21 Feb 2011 06:06:37 +0100, "Soeren Gebbert"
<soerengebbert at googlemail.com> said:
> Hi,
> You can try r.to.rast3elev which will do exactly what you need.
> 
> Best
> Soeren
> 
> Am 21.02.2011 02:38 schrieb <grass at sundquist.imapmail.org>:
> > Hamish:
> >
> > I looked at that before and the only thing I could think of was to use
> > r.to.rast3 by first generating a whole series of horizontal surfaces
> > with r.mapcalc, one for each foot of elevation, with each cell getting a
> > value of "1" if the "elevation" for that particular new surface lied
> > between the corresponding cell values of the top and bottom surfaces.
> > Then taking those whole bunch of surfaces and feeding them to
> > r.to.rast3. But that seemed pretty inelegant. But it may be only way
> > to do it. I would only be about 25 rasters to generate and then merge.
> >
> > J.S.
> >
> > On Sun, 20 Feb 2011 17:14:39 -0800 (PST), "Hamish" <hamish_b at yahoo.com>
> > said:
> >> J.S. wrote:
> >> > I want to generate a 3D raster (and display in nviz) that is
> >> > the volume between two 2D elevation rasters.  The application
> >> > is to visualize the subsuraface area that will be subject to
> >> > environmental remediation.
> >>
> >> maybe this summary helps,
> >> http://grass.osgeo.org/wiki/Help_with_3D
> >>
> >>
> >> Hamish
> >>
> >>
> >>
> >>
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