1 - NGA

I
MIL-HDBK-850
adopted by Ihe Etavemh General Conference of
Weights and Measures In 1960.
Interoculsrr dlatance-(JCS) The distance
between the centers of rotation of the eyeballs
of an Irdfvldual or between the oculars O( opfiial
Instruments. Afso called eye berse;
Interpuplllary dletance.
lnteroperablllty-Consistency between
dflerent MC&G software and data sets in ferms
of eccaracy, data structure, lealure coding, georetererrcing
systems, daturna, epatial
raaolutiina, and pracision, whch allow them to
be used on cWterent kinds of equipment
ayetarna.
Interpolate-To determine intermediate
values between given fixed values. As applied
to logical contouring, 10 interpolate is to ratio
vertical distances between given apol
elevations.
Interpuplllary dlslance—See Inter-ocular
dlrstence.
tntorrogatlon—Transmission of a radio signal
or cembirsakm of signals intended to trigger a
wansponder or group of transponders.
lntOrrOgatOr.reepOnaOr-A radio Iransmiller
and receiver combined to interrogate a
transponder and display the resulting replies.
Also called challenger. See also
Interrogator.
Interrogator-1. A radar set or other
electronic devbe that transmits an interrogation.
2. An interrogator responscrr or the transmitting
component of an interrogator raaponeor.
Interrupted map projection—A projection
having several standard meridians, each
careered over a continent, and with lobateshapad
eectlons of the projection plo!led from
each elandard meridian. Ttre projectbn is
broken In the ocean areas between the
oontlnenta, ttwa reducing the linear scale
dlacrepancles ard the overall shape distortion,
espaciatly toward the margins, while retaining
the equal area property.
Intersected point—See Intaraectlon
etatton.
IntersectIon etatlon-An object whose
horizontal position Is determined by
observations from other survey stalions, no
observations balng made at the object itsetf.
Where the object is observed from onty two
stations, Ihe position is termed a no-check
posltlon, as there & no prmf that such
obsewationa are free from btunders. Interaeciion
stations are either objects which would be
difficult to cccupy wtih an inatntmam, or Survey
SignafS whose positions can be detennlnad wtfh
stdficlenf accuracy without being occupied. Also
called Intersected pOlnt.
tniareectlon—1. (digital rnapplng) The
coexistence of end points et a apecWc
geographic focation; the set of all otrjeds
common to hvo or more !ntersecltng sets. 2.
(surveying) The procedure 01 detarrnining the
horizontal position 01 an unoccupied poinl
(Intersection station) by direction observations
from two or more known positions. 3.
(phologrammetry) The procedure of de!enrtlnhrg
the horizontal position of a poim by Intersecting
lines of direction oblainad photogrammetricelly.
The fines of directkkn may be obtalnad direcfly
from vertical photographs or by graphic or
mathematical rectification of tilted photographs.
See also reeectfon.
lntervalometer—A liming device for
automatically operating at specified intervals -
cenain equipment such as a camera ehufter for
the purpose of obtaining a desired end iap
between successive photograp!rs.
imervielblllty test—Any of iha saveral tests
used to determine the possible visiMfiiy abng a
sight fine in a proposed survey net. tts purpose
is to determine the existence of obstructions
along a proposed fine of sighf frum wtrich tower
and signal rtrqtsiremants may be developed.
tntemialblltty—Function which calculates area
or Ilne-of-sight which can be .aeen- from a
specific location or locations. Also termed
vlewehed modeling or vlewahed
mapping.
tnvar leveling rorS-See preclae Ievetlng
rod.
mvar pendulum—A quarter-meter pendulum
made of fnvar.
Invar acala-A measuring bar made from
Invar, Normally, one Side la graduated In the
metric system and Iha othar side in the Engllsh
system.
Invar tape-Any survey tape made of fnvar.