[GRASS-user] 3D volume interpolation help

[Carlos Grohmann]

Hi all, it's been a while :)

I have a student who needs to create volumes from a 3D points file.
The ASCII file looks like this:

741665|7187390|205.67|96|1|1|2|100|0|90
741736.92|7187280.39|193.89|90|2|1|2|92|0|90
741736.92|7187280.39|193.39|50|2|1|2|58|0|90
741665|7187390|191.03|96|1|1|2|100|0|90
741681|7187270|190.85|94|1|1|2|100|0|90

there are 181 entries, which correspond to drill core samples, so
actually we have 9 cores (same XY, different Z)

importing as a 3D vector works fine
v.in.ascii -z input=/home/guano/RQD_2.csv output=rqd_drill z=3

now set up the region:
 g.region t=210 b=125 tbres=1 res3=1 -p3
projection: 1 (UTM)
zone:       21
datum:      ** unknown (default: WGS84) **
ellipsoid:  sam69
north:      7187390
south:      7187270
west:       741665
east:       741761
top:        210.00000000
bottom:     125.00000000
nsres:      1
nsres3:     1
ewres:      1
ewres3:     1
tbres:      1
rows:       120
rows3:      120
cols:       96
cols3:      96
depths:     85
cells:      11520
3dcells:    979200


OK, now on to interpolation (int_1 is the 4th col):

 v.vol.rst --overwrite input=RQD_2 wcolumn=int_1 segmax=10 npmin=10
dmin=0.05 elev=teste3d
181 records selected from table
WARNING: strip exists with insufficient data
Processing all selected output files will require 46080 bytes of disk space
for temp files

WARNING: There is less than 700 points for interpolation, no segmentation
         is necessary, to run the program faster, set segmax=700 (see
         manual)
Percent complete:  100%
Finished interpolating

The number of points in vector map is 181
The number of points outside of 2D/3D region 0
The number of points used (after reduction) is 181

OK, let's see what happened:
 r3.info teste3d
 +----------------------------------------------------------------------------+
 | Layer:    teste3d                        Date: Wed Mar 31 15:23:49 2010    |
 | Mapset:   Vertedouro_Itaipu              Login of Creator: guano           |
 | Location: test_1                                                           |
 | DataBase: /home/guano/GIS DataBase                                         |
 | Title:     ( teste3d )                                                     |
 | Timestamp: none                                                            |
 |----------------------------------------------------------------------------|
 |                                                                            |
 |   Type of Map:  3d cell              Number of Categories: 0               |
 |   Data Type:    double                                                     |
 |   Rows:         120                                                        |
 |   Columns:      96                                                         |
 |   Depths:       85                                                         |
 |   Total Cells:  979200                                                     |
 |        Projection: UTM (zone 21)                                           |
 |            N:    7187390    S:    7187270   Res:     1                     |
 |            E:     741761    W:     741665   Res:     1                     |
 |            T:        210    B:        125   Res:     1                     |
 |   Range of data:   min =         98 max =         98                       |
 |                                                                            |
 |   Data Source:                                                             |
 |                                                                            |
 |                                                                            |
 |                                                                            |
 |   Data Description:                                                        |
 |    generated by v.vol.rst                                                  |
 |                                                                            |
 |   Comments:                                                                |
 |    v.vol.rst input="RQD_2 at Vertedouro_Itaipu" wcolumn="int_1" tension=40\   |
 |    . smooth=0.1 segmax=10 npmin=10 dmin=0.05 wmult=1.0 zmult=1.0 elev="\   |
 |    teste3d"                                                                |
 |                                                                            |
 +----------------------------------------------------------------------------+


So, I got a map with min=max=98 (which is the mean value of that column).

OK, what are we doing wrong? I got to admit I'm new to 3d interpolation.


best

Carlos







v.vol.rst --overwrite input=RQD_2 at Vertedouro_Itaipu wcolumn=int_1
segmax=1 npmin=1 dmin=0.005 elev=teste3d

-- 
Prof. Carlos Henrique Grohmann - Geologist D.Sc.
Institute of Geosciences - Univ. of São Paulo, Brazil
http://www.igc.usp.br/pessoais/guano
Linux User #89721
________________
Can’t stop the signal.