1 - NGA

MIL-HDBK-850
performing sight reductions, psrticufsrfythoee for
determining computed atfiiude for comparison
with tha obsetved altitude of a cefastisl body to
d~errrine the attiiude diierenca for estaMtimg
e fine of poaitbn.
sight reductlo~?’he pnxaaa of deriving
tmm cbaervation d a caleslisi bdy the
information naedad for aefsbkshing a fine d
positiin.
sight rod-See rang. rod.
sight trae-See line tma.
slght~ssrvatlon of the altitude, end
semetimes efao the azimuth, d a celaefisl bedy
fer a fine of position; or the data obtainad by
such observati.m.
slgnatura-lhe characferiefix or psfterns of
phys”kal features that permit objects to be
recognized on aerial imagery. A ceIegory is said
to have a siansture onkv il the cherscferistic
pattern is hi~hly repr~ntative of all units of that
category.
slgnlflcanl data-llw date that represents -
the best eppmxirnattin of the date of the
product’s informs!ion; e.g., the date of
Cmnpifstii or the date of the source msterials
used 10 revise the product.
slmpla conle chart-A chsrf on a simple
conic prqecfion.
simple conic map projection-A conic map
projection in which the surface o! a sphere or
sphsmid, such as the Earth, Ls sorrceivsd as
dwelaped on a tangent cone, whiih is then
spread oul to form a plane.
simple feature-See feature.
slmplo harmonic motion—lhe projection of
uniferm circular rmtion on a d~meter of the
Cide of such motion.
simple pendulum-A theoretical concept. A
heavy particle suapandad from a freed point by
a fins thread which is inexfensibla end withouf
weight. A simple pendulum cannot ba realized
in ecfual work. A simple pendulum is, however,
Ihe basis of rsdtiions of obaarvations made
with an astusl pendulum. Thoaa ebservatione
have cormrctiona sppfied to them to obtain
resufls wtich woufd have been prodmxd by an
232
equivalent simple pendulum.
●lmplifkatlon-Smoc4 hing the characfar of
feafums withotd destroying thrir vidbk skwpa.
Sit’r@iiiticm incras.sas as map Scala decreases.
Slmpaon’o 1/3 rule-A mathematical
expmasion for d~enninkrg arass between en
irmgufar boundary and a trsvarsa fiie tire
aquslly spscad offset msssuramsnts have been
Iakan.
●imultarwous aftltudea-ltfliiudaa of two or
rnera dsdial fxufies drserved at the same
tima.
simultaneous double line-sea
slmultaneoua level line.
aimultanecrua Ievef fine-A line of spiril
Iwefing c9nqxxad of two singla tinaa run over
the same mule, both in the same direction, but
using dflerent turning points. Alse cslld
elmultaneous double Ilne.
simultaneous mode-A satellite method for
delarmining the position of an unknown station
by the simultaneous ‘ranging’ fmm thrse stations
of known pmsiticm and the unknown siation, or
5imuftane0u51y obseming direction fmm fwe
stations of krrovm pesifion and the unknown
stat”km, and matharnatioally reducing ths data to
sohe for a fine or aurfaca of position of tha
unknown. TMs technique permits Pc6ifien
determination independent of a satellite’s orbital
paramatars.
aimultaneoua obaervetlono—(satallite)
0b5arvations of a sstefliia that are made from
two or mora distincl peints or tracking sfst”krns at
assctfy tha -me tima.
●htgla ●etronomlc station datum
orlentatlorr-Tha orientation of a geodetic
datum by accepting tha a6tmnomfcaIty
determined aacidinstes of tha Ori@n and ths
azimulh to one other sfatien without any
curracfion.
single proportionate measurement— A
mathcd of properfioning rnassuramenls in the
restorstkrn of e ksst comer whose position is
determined with raferenca to alignmant in ona
duacfion. Ezarr@es of sush comars are quarter
secfien canera on the fins between two section
comers, all oorrwm on standard paralbta, and all
krtenrmdiata positions on any township
boundary fine. Tha ordiiry fmkf problam