[GRASS-user] v.vol.rst : doubts about parameter "zmult"

[Eduardo corbelle]

Thank you Markus.

That makes sense for me, I have horizontal distances between points of
around 1-2 km, and vertical distances range between 10-20 m. Further trials
with "v.vol.rst -c" showed better results for zmult=50-100, getting worse
both for higher and lower values of zmult.

Regards

Eduardo

2008/10/6 Markus Neteler <neteler at osgeo.org>

> On Fri, Oct 3, 2008 at 9:27 AM, Eduardo corbelle
> <eduardo.corbelle at gmail.com> wrote:
> > Hello list:
> >
> > I've been working recently with v.vol.rst and I have doubts about
> > the real function of the parameter "zmult": the manual says it allows
> > the user to re-scale (change units of) the z coordinates of the data; but
> > I obtain better results when using high values (about 20) of zmult even
> if
> > no unit transformation (re-scaling) is needed at all (all data in
> metres). Could
> > anyone give me a
> > hint on the actual role of zmult in the interpolation process? Is it
> > reasonable to use "very" high values (e.g. 100)?
>
> Helena once told me:
>
> Rescaling of z-coordinates is for example needed when the distances in
> vertical direction are much smaller than the horizontal distances, if
> that is the case, the value of zmult should be selected so that the
> vertical and horizontal distances have about the same magnitude.
>
> Might this help as explanation?
>
> Markus
>
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