justin@inmet.UUCP (12/03/87)
Well, when you bring highways into it, it can get *really* weird --
Example: at one point, south of Boston, route 128 South is the same road
as I-93 North, which at that point, is travelling East-West! Things look
roughly like this:
--------
/ \
/ \
Route 128 --> | Boston
|
\ /
---------
/
/ <-- I-93
I don't know anyone who has managed to explain these circular roads
in decent English.
:-) Justin du Coeur
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Disclaimer: No one knows who I am, anyway, so who am *I* to dictate policy?gjs@inmet.UUCP (12/07/87)
> 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 --
marty1@houdi.UUCP (M.BRILLIANT) (12/11/87)
In article <123300003@inmet>, gjs@inmet.UUCP writes: > > Some directions arise from language evolution. Freeways have no > entrances, only exits. What is the origin of the term "down east" in > Maine? Travelers are told to hold their maps so the direction they face is up. Early colonists were going west, so their maps were read with west up, so east was down. The Romans, of course, going east to conquer, "oriented" their maps, so east was up. M. B. Brilliant Marty AT&T-BL HO 3D-520 (201)-949-1858 Holmdel, NJ 07733 ihnp4!houdi!marty1