[GRASSLIST:3606] v.surf.idw

GRASS GRASS user
1

hello,

i try to interpolate my meteorological data with the following vector data:

rsdb=> select * from temp20000130180000;
    x | y | z | parameter | data | refper | name
---------+---------+------+-----------+------+--------+---------------------
10.7814 | 46.7581 | 2070 | 4 | -7 | 0 | Kurzras
11.1667 | 46.6734 | 392 | 4 | 34 | 0 | Meran
    10.5 | 46.9 | 1360 | 4 | 25 | 0 | Nauders
  11.023 | 46.8672 | 1938 | 4 | -2 | 0 | Obergurgl
  10.875 | 46.9242 | 2850 | 4 | -44 | 0 | Pitztaler Gletscher
10.8794 | 46.9269 | 2850 | 4 | -46 | 0 | Pitztaler Gletscher
  10.913 | 46.8594 | 1906 | 4 | -1 | 0 | Vent
(7 rows)

rsdb=> \d temp20000130180000
       Table "public.temp20000130180000"
  Column | Type | Modifiers
-----------+-----------------------+-----------
x | double precision |
y | double precision |
z | integer |
parameter | integer |
data | double precision |
refper | integer |
name | character varying(20) |

rsdb=>

first question:

can anyone tell me how to set a mask as mentioned in the v.surf.idw as the
command r.mask is neither documented nor does it work on my grass57

second question:

interpolationg with r.surf.idw all cells does have the same value !?
i played around with the attribute field, to catch the required collumn
'data'. it seems that i got it as every cell has '-2' which matches only to
this collumn.
by the way, i casted my int data to float as v.surf.idw matches field='which
decimal attribute'. is this redundant?

GRASS 5.7.-cvs:~/diss/grassdata > v.surf.idw in=temp20000130180000
out=temp20000130180000 field=4
v.surf.idw:
WARNING: Vector used instead of sites.
Reading sites map (temp20000130180000) ... 6 sites loaded
Interpolating raster map <temp20000130180000> ... 2800 rows ... done
GRASS 5.7.-cvs:~/diss/grassdata > d.rast temp20000130180000
100%
GRASS 5.7.-cvs:~/diss/grassdata > d.what.rast

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196272.91666667(E) 5215609.58333333(N)
temp20000130180000 in sabine57, quant (-2)
temp20000130180000 in sabine57, actual (-2.000000)

169731.25(E) 5184692.91666667(N)
temp20000130180000 in sabine57, quant (-2)
temp20000130180000 in sabine57, actual (-2.000000)
GRASS 5.7.-cvs:~/diss/grassdata >

any advice welcome! thanks a lot.

yours, sabine

2

How did you make your vector temp20000130180000?
I guess that you have run something like
cat temp20000130180000 | v.in.ascii catcol=4
In that case a category assigned to ALL points is '4'
and all points are linked to 4. row (data = -2).
Try to query the vector by d.what.vect.

Radim

On Monday 07 June 2004 14:12, Sabine Grabner wrote:

hello,

i try to interpolate my meteorological data with the following vector data:

rsdb=> select * from temp20000130180000;
    x | y | z | parameter | data | refper | name
---------+---------+------+-----------+------+--------+--------------------
- 10.7814 | 46.7581 | 2070 | 4 | -7 | 0 | Kurzras
11.1667 | 46.6734 | 392 | 4 | 34 | 0 | Meran
    10.5 | 46.9 | 1360 | 4 | 25 | 0 | Nauders
  11.023 | 46.8672 | 1938 | 4 | -2 | 0 | Obergurgl
  10.875 | 46.9242 | 2850 | 4 | -44 | 0 | Pitztaler Gletscher
10.8794 | 46.9269 | 2850 | 4 | -46 | 0 | Pitztaler Gletscher
  10.913 | 46.8594 | 1906 | 4 | -1 | 0 | Vent
(7 rows)

rsdb=> \d temp20000130180000
       Table "public.temp20000130180000"
  Column | Type | Modifiers
-----------+-----------------------+-----------
x | double precision |
y | double precision |
z | integer |
parameter | integer |
data | double precision |
refper | integer |
name | character varying(20) |

rsdb=>

first question:

can anyone tell me how to set a mask as mentioned in the v.surf.idw as the
command r.mask is neither documented nor does it work on my grass57

second question:

interpolationg with r.surf.idw all cells does have the same value !?
i played around with the attribute field, to catch the required collumn
'data'. it seems that i got it as every cell has '-2' which matches only to
this collumn.
by the way, i casted my int data to float as v.surf.idw matches
field='which decimal attribute'. is this redundant?

GRASS 5.7.-cvs:~/diss/grassdata > v.surf.idw in=temp20000130180000
out=temp20000130180000 field=4
v.surf.idw:
WARNING: Vector used instead of sites.
Reading sites map (temp20000130180000) ... 6 sites loaded
Interpolating raster map <temp20000130180000> ... 2800 rows ... done
GRASS 5.7.-cvs:~/diss/grassdata > d.rast temp20000130180000
100%
GRASS 5.7.-cvs:~/diss/grassdata > d.what.rast

Buttons
Left: what's here
Right: quit

196272.91666667(E) 5215609.58333333(N)
temp20000130180000 in sabine57, quant (-2)
temp20000130180000 in sabine57, actual (-2.000000)

169731.25(E) 5184692.91666667(N)
temp20000130180000 in sabine57, quant (-2)
temp20000130180000 in sabine57, actual (-2.000000)
GRASS 5.7.-cvs:~/diss/grassdata >

any advice welcome! thanks a lot.

yours, sabine