[GRASSLIST:4377] v.surf.rst - problems

[Maciek Sieczka]

Hi!

Could somebody give me a hand?

I'm trying to make a DEM out of digitized elevation contours and sites using
v.surf.rst in Grass5.3.

The default settings in.v.surf.rst do not give a good result (please see
that attached nviz.jpg,10xEXAGERATED, a snapshot of the DEM
v.surf.rst made).

I find it difficult to fully understand the meaning of all the parameters to
be able to adjust them all so I could get a reasonable DEM. I did some trial
and error but never got really good result (though better than the one on
the nviz.jpg) and such method is darn slow. Besides
it's like trying to resolve an eqaution with at least 4 unknowns - I think
that
dmin, dmax, segmax, npmin are the parameters which I should be mainly
concerned with (?).

I'm asking if anyone could point me more/less how I should modify these 4
parameters in v.surf.rst and so I could get something reasonable to begin
with and then start fine-tuning on my own. Some info below and the
attached pictures should give you a clue what sort of data I'm working with.

Is there maybe some other source of information on how the v.surf.rst in
Grass work besides the manual (and the Mitasova's papers)?



GRASS:~ > g.region -p
projection: 0 (x,y)
zone:       0
north:      3916
south:      960
west:       738
east:       6699
nsres:      1
ewres:      1
rows:       2956
cols:       5961
[Raster MASK present]



GRASS:~ > v.info contours
+---------------------------------------------------------------------------
 | Layer:    contours                         Date:
 | Mapset:   bufor                          Organization: rzezba zlewni
 | Location: nieszkowicki                   Name of creator:
 | DataBase: /home/grassdata
 | Title:     ( rzezba)
|---------------------------------------------------------------------------
 |   Type of Map:  Vector (level: 2)        Number of Categories: 1000
 |                                          Number of lines:      80
 |                                          Number of areas:      0
 |                                          Number of islands:    0
 |
 |   Projection: x,y (zone 0)
 |            N:       4024    S:        814
 |            E:       6892    W:        446
 |
 |   Source date:
 |   Original scale 1:10000
 |   Map threshold: 7.62000
 |   Comments:
+---------------------------------------------------------------------------
[Raster MASK present]



GRASS:~ > v.surf.rst input=contours elev=dem

Percent complete: Warning: strip exists with insufficient data

Warning: ignoring 144103 points -- too dense

The number of points from vector file is 345152
The number of points outside of region 0
The number of points being used is 201049

Processing all selected output files
will require 141681888 bytes of disk space for temp files

bitmap mask created
Percent complete: Warning: taking too long to find points for
interpolation--please change the region to area where your points are.
Continuing calculations...Warning: taking too long to find points for
interpolation--please change the region to area where your points are.
Continuing calculations...Warning: taking too long to find points for
interpolation--please change the region to area where your points are.
Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...Warning:
taking too long to find points for interpolation--please change the region
to area where your points are. Continuing calculations...Warning: taking too
long to find points for interpolation--please change the region to area
where your points are. Continuing calculations...Warning: taking too long to
find points for interpolation--please change the region to area where your
points are. Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...Warning:
taking too long to find points for interpolation--please change the region
to area where your points are. Continuing calculations...Warning: taking too
long to find points for interpolation--please change the region to area
where your points are. Continuing calculations...Warning: taking too long to
find points for interpolation--please change the region to area where your
points are. Continuing calculations...Warning: taking too long to find
points for interpolation--please change the region to area where your points
are. Continuing calculations...Warning: taking too long to find points for
interpolation--please change the region to area where your points are.
Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...
Warning: taking too long to find points for interpolation--please change the
region to area where your points are. Continuing calculations...
history initiated
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