Institutional Afftliatie of Kmerican 6ongress on Surveying and ... - CLSA
Institutional Afftliatie of Kmerican 6ongress on Surveying and ... - CLSA
Institutional Afftliatie of Kmerican 6ongress on Surveying and ... - CLSA
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emizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the PLSS report involving<br />
acquisiti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> digital coordinates<br />
from existing files, maps<br />
<strong>and</strong> archival survey data. Thus, iniificantly<br />
increase the availability<br />
pensive GPS technology may sig-<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> rehable property boundary corner<br />
coordinate data for multipurpose<br />
boundary overlay applicati<strong>on</strong>s. Producers<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> mechanically digitized<br />
property maps should reevaluate<br />
the data capture possibilities now<br />
available through use <str<strong>on</strong>g>of</str<strong>on</strong>g> the Global<br />
Positi<strong>on</strong>ing System.<br />
A c<strong>on</strong>troversy exists with respect<br />
to multipiarpose l<strong>and</strong> record informati<strong>on</strong><br />
system development. Two<br />
points <str<strong>on</strong>g>of</str<strong>on</strong>g> view are held. One holds<br />
that easily obtained (less costly)<br />
data sets may be incorporated into<br />
the new system first, leading to certain<br />
immediate system products<br />
<strong>and</strong> benefits. Then, additi<strong>on</strong>al data<br />
sets (more costly) may be incorporated<br />
later, as time <strong>and</strong> m<strong>on</strong>ey<br />
allow. The basic argument <str<strong>on</strong>g>of</str<strong>on</strong>g> those<br />
holding this view is that geodetic<br />
c<strong>on</strong>trol, <strong>and</strong> property boundary corner<br />
coordinates <str<strong>on</strong>g>of</str<strong>on</strong>g> sufficient accuracy<br />
to be c<strong>on</strong>sidered for legal<br />
use, are assumed to be too costly<br />
<strong>and</strong> are lumped into an 'incorporate<br />
ter if necessary' data set.<br />
The sec<strong>on</strong>d view holds that the<br />
geodetic c<strong>on</strong>trol framework <strong>and</strong><br />
legal property boundary overlay<br />
data sets must be substantially in<br />
place before additi<strong>on</strong>al sets are incorporated<br />
into any developing multipurpose<br />
informati<strong>on</strong> system. The<br />
basic arguments supporting this<br />
view are that precise geodetic c<strong>on</strong>trol<br />
data cannot efficiently be added<br />
later to a series <str<strong>on</strong>g>of</str<strong>on</strong>g> spatially disjointed<br />
overlays <strong>and</strong> that it is much<br />
more efficient to tie the additi<strong>on</strong>al<br />
overlays directly to <strong>on</strong>e legal property<br />
boundary corner data set<br />
rather than try to tie the legal property<br />
boundary data set to a series <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
spatially disjointed sets.<br />
The c<strong>on</strong>tinued high cost <str<strong>on</strong>g>of</str<strong>on</strong>g> quaUty<br />
GPS receivers, the promise but not<br />
full development <str<strong>on</strong>g>of</str<strong>on</strong>g> the complete<br />
GPS c<strong>on</strong>figurati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> sateUites, <strong>and</strong><br />
the uncertain nature <str<strong>on</strong>g>of</str<strong>on</strong>g> civilian access<br />
add just a hint <str<strong>on</strong>g>of</str<strong>on</strong>g> cauti<strong>on</strong> to<br />
GPS expectati<strong>on</strong>s. Ten years ago,<br />
inertial technology appeared to be<br />
the ultimate "black box!' Signifint<br />
price reducti<strong>on</strong>s did not occur,<br />
owever. <strong>and</strong> except for a real-time<br />
positi<strong>on</strong>ing capability, use <str<strong>on</strong>g>of</str<strong>on</strong>g> the inertial<br />
technology appears to be<br />
dwindling.<br />
Total reliance <strong>on</strong> any <strong>on</strong>e technology<br />
would be foolhardy, especially<br />
c<strong>on</strong>sidering the real vulnerabiUty<br />
that 18 GPS satellites will exhibit in<br />
an era <str<strong>on</strong>g>of</str<strong>on</strong>g> superpower Star Wars capability.<br />
C<strong>on</strong>tinued development <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
alternative ground-based positi<strong>on</strong>ing<br />
technology must be insured.<br />
R<strong>on</strong> Hogan recently predicted that<br />
by 1990, a cost effective real-time instantaneous<br />
XYZ coordinate measurement<br />
device will be available.<br />
(Miller, 1985) Whether or not GPS<br />
can become a real-time stakeouttype<br />
technology in the near future,<br />
an alternative positi<strong>on</strong>ing technology<br />
is required.<br />
A major comp<strong>on</strong>ent <str<strong>on</strong>g>of</str<strong>on</strong>g> most c<strong>on</strong>structi<strong>on</strong><br />
projects in the field is the<br />
layout or stakeout process. Establishing<br />
the horiz<strong>on</strong>tal positi<strong>on</strong>s<br />
<strong>and</strong>/or vertical positi<strong>on</strong>s <str<strong>on</strong>g>of</str<strong>on</strong>g> many<br />
sets <str<strong>on</strong>g>of</str<strong>on</strong>g> points (<str<strong>on</strong>g>of</str<strong>on</strong>g>ten more than <strong>on</strong>ce<br />
per point) are required. Laser level-<br />
Ung <strong>and</strong> c<strong>on</strong>tinuous readout distance<br />
meter technologies have automated<br />
these field layout procedures,<br />
but current technology still requires<br />
more than <strong>on</strong>e crewpers<strong>on</strong> to make<br />
horiz<strong>on</strong>tal applicati<strong>on</strong>s <strong>and</strong> more<br />
than <strong>on</strong>e piece <str<strong>on</strong>g>of</str<strong>on</strong>g> equipment if both<br />
horiz<strong>on</strong>tal <strong>and</strong> vertical determinati<strong>on</strong>s<br />
must be made.<br />
Satellite positi<strong>on</strong>ing units using<br />
GPS satelUtes do exist today that<br />
can provide accurate 3-dimensi<strong>on</strong>al<br />
point positi<strong>on</strong>ing (± 1cm) <strong>on</strong> the<br />
ground. These units are not realtime,<br />
their cost is exorbitant, they<br />
are heavy or bulky, <strong>and</strong> they are currently<br />
usable <strong>on</strong>ly about 6 hours out<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> 24 due to insufficient numbers <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
orbiting satelhtes.<br />
Currently available total stati<strong>on</strong><br />
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