[GRASS-user] Re: [GRASS-dev] Some comments on the v.surf.icw add-on

Hamish hamish_b at yahoo.com
Sun Jan 10 15:05:37 EST 2010

Ben wrote:
> Max cost would be great in combination with an option to
> set each output cell to NULL which is located > maxcost
> from any input point.

That is the main purpose of having the post_mask option btw.
I can see value in setting the NULL mask much smaller than
how far you let a point's influence travel though. I think it
is conceptually two different kinds of error.
e.g. I surmise there was trade-connectivity between the east and
west coasts of the continent, but I don't think there were very
many individuals traveling more than a few hundred km themselves.

> > luckily there is a simple polynomial which fits my hand
> > calculated correction almost perfectly.
> That is lucky indeed (and probably good prove that your
> correction factor was sound in the first place)!

well really it isn't that much luck. I'm not in the habit of
just pulling numbers out of thin air; I would have calculated
the originals by normalizing the output of some idealized test
case to some common value.



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