[GRASS-user] Creating a ground water from a vector files ofcontours?

Moskovitz, Bob Bob.Moskovitz at conservation.ca.gov
Tue Feb 6 18:34:38 EST 2007

Hi Brad,

Your email is full of good tips...thanks!  


-----Original Message-----
From: Brad Douglas [mailto:rez at touchofmadness.com]
Sent: Monday, February 05, 2007 10:07 PM
To: Moskovitz, Bob
Cc: Grassuser (E-mail)
Subject: Re: [GRASS-user] Creating a ground water from a vector files

On Mon, 2007-02-05 at 12:50 -0800, Moskovitz, Bob wrote:
> Hello Grassusers,
> Like the subject line says, I need help creating a ground water map
> using a vector file of contours.  The ground water file came from a
> E00 file that was read into Grass using v.in.e00.  I am currently
> running v.surf.rst which is taking a long time to run.  Are there
> other ways to do this problem?


As you've discovered, v.surf.rst is quite computationally intensive.
Depending on your needs, here are a some suggestions that may help:

- When using RST, experiment with a small region to setup parameters
properly.  It will save a lot of time in the long run.
- Reducing resolution will speed calculations.
- Setup several overlapping regions, run each one on a separate CPU,
crop outlying data, and r.patch them together.  This unfortunately
allows plenty of room for human error and may introduce seams.
- Depending on level of "accuracy" and output desired, v.surf.bspline
and v.surf.idw may be less expensive alternatives.

In the past, I have setup my RST parameters and "set it and forget
it" (to borrow from RonCo. :-).  I came back a week later and I was
ready to start doing real work.

Others may have better ideas...

Brad Douglas <rez touchofmadness com>                    KB8UYR/6
Address: 37.493,-121.924 / WGS84    National Map Corps #TNMC-3785

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