[GRASSLIST:1585] Re: interpolate nominal values

[Thotapalli, Hari Kishore - THOHK002]

Apologies for butting in. A very interesting conversation topic indeed. Having
learnt some new things in terms of gis applications from this thread I wish to
take this opportunity to inquire if r.fuz* modules very recently introduced in
grass would be of any help ?

regards

Hari Kishore THOTAPALLI
PhD Candidate
School of Geoinformatics Planning and Building
University of South Australia
Adelaide
 

-----Original Message-----
From: Lyle E. Browning [mailto:lebrowning at worldnet.att.net]
Sent: Friday, 9 March 2001 1:57 PM
To: Rich Shepard
Cc: grasslist at baylor.edu
Subject: [GRASSLIST:1582] Re: interpolate nominal values




Rich Shepard wrote:

>
>   This is a flour from a different mill. Performing a nearest-neighbor
> analysis by fitting Veronoi polygons around each fast-food outlet will show
> all the points that are closer to one burger than another. However, while
> this is interpolation (finding the midline between all adjacent pairs of
> points) you could not proceed to build an elevation model from it and have
> the resulting surface mean anything.
>

Not having done any of that, I couldn't begin to argue otherwise. But, ;>), in
looking at the patterns generated in relation to the surrounding areas, we'd
end up
with a good idea of where the prehistoric McDonald's were built and extrapolate
to
locate others. We might think of them as temples. Areas for seating of the
worshippers, priestly areas wherein burnt offerings are prepared, all the
trappings
of ritual behavior previously observed. Personally, I cannot imagine an
archaeologist 200 years down the road digging one of them, but then again, they
may
by then be of such rare status that they will achieve importance beyond their
mere
presence.

>
>   With the soils data that initiated this thread, the point represents an
> area. Veronoi polygons don't mean anything here, and producing a 3D surface
> map is equally meaningless. And that's where the discussion went: how do you
> interpolate a surface from the point data?
>

Not having been there, and not having done that, I can't argue again. My own
experience is that archaeology is still in relative infancy and just the
exercise of
obtaining points, putting them through their paces and identifying data gaps is
extremely useful. Of course, after the gaps are filled, it still remains to be
seen
what it all means. I'm still in the data acquisition mode rather than the
synthesis
mode.

>
>   Perhaps you build 3D continuous surfaces from pottery shards or flour mill
> locations, and it means something within the field of archaeology. But, as
> a quantitative ecologist, I'd map the soils data and all I could say is
> that's the soil type at this point. Period.
>

We'd look at soils and examine site locations. Certain soil types attract
prehistoric and sometimes historic occupants. The inverse is also true. We have
looked at very good productive soils and found that the prehistoric types who
were
incipient horticulturists avoided them and camped on the adjacent types. That's
a
data gap we have and need to fill. We're still far too much into the individual
site
and what it means relative to other excavated sites versus using a GIS to
synthesize
the spatial aspects of what we already know and see where it leads.

We typically look at pottery distributions from a site and see where activities
took
place and who did what. Assuming that the info is there to work with and it's
not
all uniform, the distribution of different pottery types can tell the
socio/economic
status of the inhabitants, big house versus worker activity locations, craft
locations, etc.

The Park Service examined the Little Big Horn battlefield, located and mapped
bullets and from the known info on what caliber guns the 7th Cavalry had versus
what
else was found, it was shown that the Sioux had better guns and all sorts of
interesting interpretation was possible from those points. Not elevation models
there, granted, but at basis, the first level analysis was fascinating. That's
primarily where we're going at a snail's pace in my profession.

>
> "everything is a variable. Nothing is
> a constant. How can you make sense of it?" "Statistics,"

> Lies, damned lies and statistics. Now add the never ending problem that in
> archaeology you're not dealing with the full universe of what was on the
site, but
> only that which survives. And then you attempt to make some form of reality
out of
> it. Constant reiterations are required. New info comes in, out goes the old
model
> after much argument.

>
> Knowing the mechanics of running the software does not qualify the operator
> as a spatial analyst. As we are all well aware, teaching someone how to
> manipulate a word processor does not make him a good writer. I like this
> discussion.

Proof's in the pudding, as always.