Path: utzoo!mnetor!uunet!husc6!cca!mirror!ishmael!inmet!gjs
From: gjs@inmet.UUCP
Newsgroups: comp.cog-eng
Subject: Re: spatial reference in natural langua
Message-ID: <123300003@inmet>
Date: 7 Dec 87 15:18:00 GMT
References: <6818@sunybcs.UUCP>
Lines: 49
Nf-ID: #R:sunybcs.UUCP:-681800:inmet:123300003:000:2400
Nf-From: inmet.UUCP!gjs    Dec  7 10:18:00 1987


> We would be interested in examples of the use of non-cartesian
> coordinate systems for specifying directions, and also of uses of
> "up", "down", and other such terms in direction-giving and
> spatial reference.

Of course, compass directions are a non-cartesian system, because lines
of latitude are not parallel.  In most inhabited areas, the cartesian
system is a good approximation to north-south east-west.  The use of
the approximation is so ingrained that some people are confused by old
riddles such as:

    A man is in a square room, in which each wall has a window with a
    southern view.  A bear enters the room.  What color is the bear?

It would be interesting to find out what directions Eskimoes use,
because the sun is so low and the pole star is so high.

Astronomers use a spherical coordinate system of right ascension and
declination, which are like latitude and longitude.  The interesting
thing is that right ascension is in units of time rather then angle, so
that conversion from absolute position to relative position can be done
simply by subracting Greenwich mean time.  It would be so much easier
if those pesky stars didn't move around.  I don't know whether
astronomers compare two right ascensions with terms "east" and "west,"
or "earlier" and "later."

Time also appears as a measure of distance in expressions such as
"twenty minutes north of Boston."

Radial coordinate systems may be from an arbitrary origin.  Navigation
frequently involves going some distance on some heading, then going
another distance on another heading.  Orienteering, military navigation
on land, and ship navigation are examples.  Headings may be relative to
current direction, as in "bear two degrees to port."

Some directions are completely abstract.  In a text editor, moving
"left" on a line means "towards the start of the file."  "Up" a line
means the same thing, but by a larger amount.  "Back" a page is still
larger.  "Up" in a tree structure means "towards the root of the tree."
One can "go into" a directory.  These terms come from a conceptual
mapping, i.e.  different representations or "views" of the same data.
Perhaps this is not what you are looking for.

Some directions arise from language evolution.  Freeways have no
entrances, only exits.  What is the origin of the term "down east" in
Maine?

    --  George Snyder  --  Intermetrics, Inc.  --  gjs@inmet  --