indeed it might be loveliest if these conversations inspired someone to recall to mind
or more likely & even better yet to create for the first time ever
such a delicately poised multipoint try
that one might use an ordinary gpsr to first completely cover & then completely miss
the legally defined target window
simply by switching datums
& if there is one to be had i think nyonqc could be that one
& the ibc may even now be getting us all the data necessary to actually demonstrate this
too
haha
what fun
--- In BoundaryPoint@yahoogroups.com, "aletheiak" <aletheiak@y...> wrote:
>
> ok thanx i get it
> but i am also still trying to figure out if there is anything useful for trypointing in these
> conversations that is somehow still eluding me
>
>
> for reasons mostly just explained
> the choice of datum has rarely if ever made a difference in our multipointing tries
>
> i dont say it absolutely couldnt make a difference but it evidently hasnt yet
>
> &
>
> such variations or deviations in data as you guys are reporting here come as no surprise
> i trust
> yet their exact cause or causes are at the same time unknown & unknowable because
> the variables are too great as well as too numerous to permit any conclusions about any
> single bit of data
> let alone any generalizations about the whole of it
> except that
> trypointing by gps might become very slightly more or less tentative approximative
fudgy
> & sketchy than it already is depending on which datum you choose
>
> so on both counts
> these observations seem to me to be not useable information but rather the absence of
it
> for our purposes here
> or at best a partial description of what is for us only a hypothetical data gap anyway
>
> the data that are most useful to us here in trypointing are those which narrow & focus
the
> search & the perception rather than diffuse them
>
> as soon as someone actually applies any of this info to a real try
> & it makes a difference in the outcome
> i would of course immediately change my appraisal of it
>
> --- In BoundaryPoint@yahoogroups.com, "Hugh Wallis" <hugh@o...> wrote:
> >
> > Each entry made records the actual WGS84 coordinates displayed on a GPSr
> > device that is positioned at a physical marker which is marking the Prime
> > Meridian. The point is to demonstrate, pursuant to the preceding
> > conversation here, that the choice of datum when reporting Lat and Long is
> > relevant. Frequently the WGS84 reading will show other than 0° 0.000" E/W
> > because different datums (data ?) than WGS84 have been used when placing the
> > physical markers. This is not a scientific survey of course, nor can it be
> > used in any way to deduce errors elsewhere. It is simply for illustration
> > and one of the larger collections of such "in the field" reports of such
> > deviations that I am aware of. It adds additional information to what Roger
> > found from Google Earth.
> >
> >
> > _____
> >
> > From: BoundaryPoint@yahoogroups.com [mailto:BoundaryPoint@yahoogroups.com]
> > On Behalf Of aletheiak
> > Sent: Tuesday, January 03, 2006 4:46 PM
> > To: BoundaryPoint@yahoogroups.com
> > Subject: [BoundaryPoint] ok but why or what are we looking for
> >
> >
> > --- In BoundaryPoint@yahoogroups.com, "Hugh Wallis" <hugh@o...> wrote:
> > >
> > > Take a look here where the difference between WGS84 and various other
> > > "observations" is documented at various locations along the prime meridian
> > >
> > > http://tinyurl.com/76jv4
> > >
> > >
> > > _____
> > >
> > > From: BoundaryPoint@yahoogroups.com [mailto:BoundaryPoint@yahoogroups.com]
> > > On Behalf Of Roger McCutcheon
> > > Sent: Tuesday, January 03, 2006 6:20 AM
> > > To: BoundaryPoint@yahoogroups.com
> > > Subject: Re: [BoundaryPoint] Four pointer
> > >
> > >
> > > I went to maximum magnification on Google Earth and found that it did
> > indeed
> > > show zero longitude as being about three quarters of the way to the far
> > side
> > > of Black Heath Avenue, to the east of the Zero Meridian in the Royal
> > > Observatory, so then I went to the Prime Meridian site and found that "the
> > > zero meridian on the WSG84 datum, which is about 100 metres to the east of
> > > the line marked at Greenwich, is an average of the various continental
> > > movements", so we need not worry: someone is paying attention! Roger
> > > McCutcheon.
>