[GRASSLIST:1308] Re: Converting sites to rasters

[Eric G . Miller]

On Wed, Dec 20, 2000 at 11:30:19AM +1100, 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?

Yes, it's either a bad region setting, or the temp file creation/open
failed, but it's not caught until later.  I just updated the CVS copy to
hopefully be a little better about this (and at least report the problem
where it occurred).  I can't be sure why program was unable to create a
temp file (it would be located as ...
<location>/<mapset>/.tmp/$HOST/$PID.nn ).

That's a big chunk of data to process at one time.

> 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?

I've had good luck using s.to.rast, then r.surf.idw.  For something big,
it should work better than the surface generation from sites (as the
textual nature of sites makes reading/parsing slower and requires a fair
amount of memory).  It will take a while to generate a surface no matter
what with that many locations.

-- 
Eric G. Miller <egm2 at jps.net>