[GRASSLIST:1306] Re: Converting sites to rasters

[Roger S. Miller]

Gordon,

I'm not particularly experienced at this, but I had a similar (but less
extreme) problem the first time I tried to generate a surface from sites
data.  I think all of your problems here might be explained *if* you did
the same thing that I did.

The raster map that is created by all of these procedures is determined by
your current region and mask settings.  Make sure that your current region
is no larger than you need it to be and that the grid resolution is no
smaller than you need it to be.

If your region settings aren't right then you may be asking grass to give
you far more than you need or want.

I think my first choice of methods would be to generate a raster map from
the sites file using s.to.rast (assuming you can get it to work) then
generate the interpolated surface using r.surf.idw or r.surf.idw2.


Roger Miller


On Wed, 20 Dec 2000, Gordon Keith wrote:

> I'm trying to use grass5b10 with bathymetry data and am having some 
> trouble getting started.
> 
> I can import my data into a sites file (approx 150,000 sites) but I 
> haven't been able to convert it to a raster.
> 
> s.to.rast gives me:
> 
>      ERROR: error while writing to temp file
> 
> Has anyone got any ideas what be causing this?
> 
> s.surf.idw seems to take about 1 CPU hour per site on my 400MHz PII (I 
> killed it after running all weekend).
> 
> s.surf.rst also seems to be taken an enormous amount of time.
> 
> My data is basic lat,lon,depth data.
> 
> I suspect I'm trying to use the wrong tools for the job, can anyone 
> suggest what I should be using?
> 
> Regards
> Gordon
>