touch at ISI.EDU
Thu Nov 13 08:48:39 PST 2008
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bmanning at vacation.karoshi.com wrote:
> On Thu, Nov 13, 2008 at 07:41:36AM -0800, Joe Touch wrote:
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>> Hi, Bill,
>> bmanning at vacation.karoshi.com wrote:
>>> isn't location defined by a set of coordinates?
>> Sure. Potentially by a region expressed as a set of coordinates.
> good... then we have a starting point for divergence. :)
>>> and they have to be found somewhere (e.g. stored)?
>> Not necessarily the way you might expect. The information of where my
>> stapler is located on my desk is stored only in the stapler itself; it
>> isn't represented in other storage.
> actually, i posit that it is. on the presumption of a shared
> coordinate space, the stapler is internally consistant (assuming
> no acceleration or vector for the stapler for the nonce) and you
> are correct in that the coordinate set is unique to the stapler.
> however, the coordinate space is only useful to third parties. i.e.
> where you (and we will leave as an exercise to the reader what & where
> define "you") are -in relation- to the stapler coordinates.
> "... move the hand 210degress down, 18cm, at 3.5cm/sec until hand reaches
> 33 59 8.376 N 118 26 48.156 W 200m at zero acceleration..." then take
> what ever you find there. (should be the stapler, right?)
You're presuming that you know the location of a device near the
stapler. How did you know that unless that location was stored somewhere
you knew? Once you know that, then yes, you can _measure_ the location
of the stapler using the sensing device at that location. At that point,
the location of the stapler would be relative to the location of the
other device as an offset - again, using information that you either had
to have pre-shared or had to obtain somehow (length of the arm, angle, etc.)
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