It is indeed possible. The 2 important issues are the way you construct the voxels and the way you visualize them.
If you want to have solid layers with sharp upper and lower boundaries (e.g., geologic strata), use r.to.rast3 or r.to.rast3elev. If you want to represent a property that varies continuously vertically (e.g., soil OM or groundwater), you need to create 3D points and do a 3D interpolation.
Once you have a volume, it just looks like a block unless you specify colors and visualize it in NVIZ with isosurfaces and/or slices. However, even if it “looks” like a block, you can still query it as a 3D volume to extract a geologic layer, for example based on its z coordinate or voxel value.
Michael
On Jun 9, 2012, at 6:04 AM, <grass-user-request@lists.osgeo.org>
wrote:
For example:
from <plangeol.jpg>to <volumo.jpg>
Is this really possible ? (it needs lots and lots of memory)
Many thanks
C. Michael Barton
Visiting Scientist, Integrated Science Program
National Center for Atmospheric Research &
University Consortium for Atmospheric Research
303-497-2889 (voice)
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu
I think that the problem is my understanding of r.to.rast3elev
The problem
http://osgeo-org.1560.n6.nabble.com/file/n4980189/sondages1.jpg
I define the 3D resolution (the lower limit of the formation is 540m and the
upper 1330m)
g.region res=200 res3=200 t=1400 b=500 tbres=20
(2d/3d resolution of 200m, top at 1400m, bottom at 500m and a
top-bottom-resolution of 20m.
I create two support maps
r.mapcalc 'one= 1'
r.mapcalc 'two= 2'
and
r.to.rast3elev --o -l input=one,two elevation=bxltop,bxlbase output=bxl
If I export to vtk the result (with the boreholes) is (with the threshold
filter = 1)
http://osgeo-org.1560.n6.nabble.com/file/n4980189/paraview1.jpg
The upper surface is correct, the lower not
http://osgeo-org.1560.n6.nabble.com/file/n4980189/paraview2.jpg
and and I do not understand why
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Ok, it works now
with the two surfaces
http://osgeo-org.1560.n6.nabble.com/file/n4980223/surfacesok.png
the volume between the surfaces:
http://osgeo-org.1560.n6.nabble.com/file/n4980223/volumesok.png
with the base surface:
http://osgeo-org.1560.n6.nabble.com/file/n4980223/volumes2ok.png
and the top surface:
http://osgeo-org.1560.n6.nabble.com/file/n4980223/volumes3ok.png
But I can not visualize it in nviz:
- I tried with isosurfaces attributes 1 and 2 or 2 only, like the threshold
values in Paraview (from r.mapcalc 'one= 1' and r.mapcalc 'two= 2' )
GRASS 6.4.2 (geol):~ > r3.univar volume20
100%
total null and non-null cells: 2410200
total null cells: 1703698
Of the non-null cells:
----------------------
n: 706502
minimum: 2
maximum: 2
range: 0
mean: 2
mean of absolute values: 2
standard deviation: 0
variance: 0
variation coefficient: 0 %
sum: 1413004
- I tried with different values associated with surfaces :
GRASS 6.4.2 (geol):~ > r.univar bxlbase
100%
total null and non-null cells: 48204
total null cells: 8133
Of the non-null cells:
----------------------
n: 40071
minimum: 463.652
maximum: 749.639
range: 285.987
mean: 577.433
mean of absolute values: 577.433
standard deviation: 87.919
variance: 7729.75
variation coefficient: 15.2258 %
sum: 23138333.880065918
GRASS 6.4.2 (geol):~ > r.univar bxlbase
100%
total null and non-null cells: 48204
total null cells: 8133
Of the non-null cells:
----------------------
n: 40071
minimum: 544.634
maximum: 1081.48
range: 536.846
mean: 842.635
mean of absolute values: 842.635
standard deviation: 126.068
variance: 15893.2
variation coefficient: 14.9612 %
sum: 33765222.471862793
But my nviz remains hopelessly empty.... (only the box outline)
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