theres an insertion about a third of the way down the page
--- In
BoundaryPoint@yahoogroups.com, "acroorca2002"
<orc@o...> wrote:
> --- In BoundaryPoint@yahoogroups.com, "Michael Donner"
> <barbaria_longa@h...> wrote:
> > actually several pleasant surprises this morning at topozone
> >
> > first
> > the long awaited topos of puerto rico & the virgin islands are
> finally being
> > filled in
> > & are now practically complete on at least one coverage level
> >
> > second
> > it is apparently now possible to use the coordinate format
> feature there to
> > get geopositions down to the nearest integral degminsecs
> > by simply clicking on any desired point
> > wow
> > & i say apparently only because i have previously found that
the
> purported
> > accuracy levels of topozone may leave something to be
> desired
> >
> > but whatever the actual range of error here of each stated
> second of
> > latitude & longitude
> > we are now surely within a few hundred feet & hopefully
within
> 100 feet of
> > the truth
> > even while we realize that the truth of the maritime tripoints
will
> be
> > elusive in any case for a host of other reasons too
>
> fortunately however
> i just realized
> an objective test of the accuracy of the topozone clickable
> degminsec unit is readily available thanx to some data that
were
> previously developed for another maritime tripoint
> oruswa
> which is in fact the clearest & least elusive of the entire set of
20
> since it is by chance pinpointed twice
>
> first in bus&ss p155 & then by the most explicit topo depiction
>
>
> http://tinyurl.com/3b5bu
> is not a mistake or an abstract art work
> but shows the click point at the maximum zoom level
> & hence presumably at the greatest possible accuracy level
>
> to see the state of the art depiction of the greater tripoint area
> select the large size & zoom out to at least the 250000 level
>
>
> & since we have already visited & studied oruswa quite
carefully
> in messages 4598 & 4713 & 4745
> we can simply borrow the data from there & compute the
critical
> longitude figure alone
> for there is actually no question about the latitude
> n46d15m00s
>
> &
> begin drum roll
> by exact calculation
> the longitude of oruswa proves to be
> not w124d09m22s
> as indicated by the topozone click
> but w124d09m20s29882863341
>
> or about 119 feet east of the click point
whoooops
thats oranges & apples
since the bus&ss data were nad27 & the click point was nad83
hahaha
so here are the bus&ss data converted to nad83
thanx to this handy site
http://jeeep.com/details/coord
nlat 46d14m59s4 x wlong 124d09m24s9
& this produces a revised error of 212 feet from the click point
which is admittedly a little offputting
for it means many of my clicks could well be not just 1 but 2 or 3
seconds off
while i was wanting & intending to pin all these tripoints right
down to the correct integral second
but clearly such exactitude is not yet within the state of the art
nevertheless i have in the meantime pinned 2 more of these
points down
at least to that limited extent
bringing me a quarter of the way now to completing the set of 20
these are
caorus
which we just revisited again in message 13243
thanx to jesper kevin & lowell & bus&ss p155
nad83 nlat 42d00m00s x wlong 124d19m56s
&
alflus
nad83 nlat 30d13m49s x wlong 87d31m07s
last revisited in message 10864
tho i have subsequently abandoned the wraparound idea
mentioned there
since a careful reading of bus&ss p105 actually precludes it
& btw i have also learned that the mullet toss also mentioned
there is not actually conducted lengthwise along the alfl state
line as reported
but rather by using the state line as the starting line for the
throws
end insertion
& thanx for your patience
>
>
> considering the large scale of the map series used for oruswa
> namely 100000k rather than the 25000k scale of the pr&vi
maps
> the narrowness of this error margin is quite remarkable
> & shows that our careful readings should indeed fall within a
few
> hundred feet
> or a second or 2
> of the truth
>
>
> end insertion
> but 17 more tripoints are still to come
>
> >
> >
> > but at last we do have the means to at least try for the exact
> degminsecs
> >
> >
> > so in view of the above 2 discoveries
> > i immediately & excitedly tried for the 2 most difficult &
> problematic of
> > the 20 tripoints in this maritime category
> > prusvin & prusvis
> > which you may recall were last revisited in
> >
http://groups.yahoo.com/group/BoundaryPoint/message/12670
> >
> >
> > now
> > tho i couldnt be absolutely sure that the maps provided by
> topozone actually
> > included the easternmost islands of the puerto rico group &
> the westernmost
> > of the virgin islands group
> > it does seem likely that
> >
http://www.topozone.com/map.asp?lat=18.3185&lon=-65.225
> > shows the base points on isla culebrita for the
eastwardmost
> projections of
> > the 3league limits of puerto rico
> > namely
> > cabo del pasaje for the northeastwardmost arc
> > & the islet just southeast of punta del este for the
> southeastwardmost
> >
> > & if you zoom this swatch all the way out to 1000000k
> > you will see where these points are in relation to all the
> easternmost
> > islands of puerto rico
> > including the entire culebra group & vieques etc
> > & indeed in relation to the northeast coast of puerto rico itself
> > as well as in relation to the westernmost of the virgin islands
> >
> > & you will also see the virgin passage that lies between
these
> 2 groupings
> > & where both of the tripoints will fall
> > on the atlantic & caribbean sides respectively of this
passage
> > & actually within the area indicated in black there rather than
> blue
> > owing to the nonexistence of topos of the open sea
> >
> >
> > & proceeding next into similar detail on the virgin side
> > it seems similarly likely that the basepoints for the
> westwardmost
> > projections of the 3mile limits are
> >
>
http://www.topozone.com/map.asp?lat=18.33778&lon=-65.0852
> 8
> > on one hand
> > for the southwesterly arc based on the islet just southeast of
> virgin point
> > on savana island
> > &
> >
>
http://www.topozone.com/map.asp?lat=18.40583&lon=-65.0608
> 3
> > on the other hand
> > for the northwesterly arc based on the islet just west of
> cockroach island
> >
> > & btw you can again find your place if necessary by zooming
all
> the way out
> > here too
> >
> >
> > so after clicking as carefully as possible on all 4 of these
> relevant base
> > points to get their best available degminsecs
> > i then mapped these points on graph paper & ran some trial
> arcs out from
> > them
> > at the respective 9nm & 3nm radii
> > in order to get rough positions for the 2 arc intersections
> >
> >
> > then with the help of this great circle calculation site
> > http://www.wcrl.ars.usda.gov/cec/java/lat-long.htm
> > i was able to check & improve the accuracy of my intersection
> projections
> > thru 6 more trials in each case in fact
> > until i finally reached fully coordinated positions of
> > nlat 18d25m46s x wlong 65d06m35s
> > or about 3nm wnw of cockroach island
> > for prusvin
> > &
> > nlat 18d17m29s x wlong 65d03m53s
> > or about 3nm actually sse of savana island
> > for prusvis
> >
> >
> > as for the best available pics
> > these are only for prusvin
> > & probably only class e
> >
http://www.vacationrentalsonline.com/vr/st/st1006/st1006.htm
> > with nothing at all yet for prusvis
> >
> >
> > but anyway
> > with both of these most difficult positions finally in hand
> > & with the considerable help already provided by lowell too
> > it should now be comparatively easy to find & zero in on the
> remaining 18
> > maritime tripoints of the usa down to the same level of
> accuracy
> >
> > then we could scarf up pix not only of but actually from all 20
of
> these
> > tripoints on a single continuous cruise
> >
> >
>
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