1 - NGA

. ..- MIL-HDBK-850
degree 01 clartty and sharpness of an image.
deflecflng force-see Corlolls force.
deflection angle traverae-A survey,
usually an open traverse, in which the
maaauremanf is made on the deflection angle
of each course or fag from Ifre direction of the
precedhfg leg. See also deflactlon angla,
dafinifion 1.
deflection angle-1. (survaying) A horizontal
angle measured from !he prolongation 01 the
preceding Ikra to the folfowing line. Defbcfion
anglaa to the right ara posttive: those 10 the left
are neQaWa. 2. (photogrammetry) A varflcal
artgla, measured in the vertical plana containing
the flight line by which the datum of any model
in a slereotriangulatad strip departs from the
datum 01 the preceding nwdel.
I deflactlon rmomaly—The difference
between an uncarected value of lhe deflection
of the varlkal as detemrinad by observation and
tha value after being cerrecfed in accordance
with Cefiain aaaumotions made with reference to
the physical condition 01 the geoid.
I
I
deflectbn of the plumb lina-Deflection of
the plumb line has tha same value as the
deflection of the vertical except the sign of the
value is reversed. See also deflactlon of fha
verslcal.
daflecflon of fha venlcal—The angular
dfierence, at any place, between the upward
dkecticn of a plumb line [ltxe verfkal) and the
pe~endkular (the normal) to the reference
spheroid. This difference seldom exceeds 30
seconds except In mountainous terrain or great
depths of the sea. Often expressed in two
OJmPnent% MSfidian and prime vertical. Also
called dafkrctlon of the plumb Ilna;
ataflon wror. See also aatrogeocletlc
daflectlon; gravlmefrlc deflactlon;
topograpnlc daflectlon.
degauaslng ranga-A station for determining
magnetic signatures of ships and other marine
craft. Such aignalures are used to determine
requlrad dtrgaussing coil currant settings and
other requlrad correcflve action.
degenerate amphldromlc eyalam— A
system of Cotidal fines whose center or nodal
(no-tkfe) point appaam to be Iocaled on land
rather than in the open ocean.
66
degrea of curva-Tha number of dagrees of
angular measure et the tamer of a circle
subtended by a chord 100 feet in length. in
highway surveying, a 100-foot arc is wrnatimes
used Instead of a 100-foot chord in defining
degree of curve.
degreaa of fraedom-The number of
independent equations that may be wrftten from
a redundant set of observations In excess of the
number of equations required for a unique
aoknion ot the unknown parameter. That is, if
from a eel of radundant observations, n
observation equations can be writfan to
associate m numbar of unknown parameters
(nzm), then the independent set ot equations
(n-m) Is known as degrees of freedom tn any
least squares adjustment of these redundant
obsewaflons The speclaf, but very mmmon,
case of establishing one parameter as the
mean ot observations establishes u-1 and m-n,
I.e., there b only one parameter and It may be
uniquely determined by any one of the
observatbns. (In this case, each observatbn is
an equation, e.g., xl-10.2). Therefora, in fhis
special case the degrees of treadom equal (n-
1),
..
delay-(JCS) 1. (radar) The ground distance
trom a poinl directly benealh the aircraft to the
beglnnlng of Ihe area of radar scan. 2. The
electronic delay of the start of the time base
used to select a particular segment 01 the total.
danelflcatlon network—Triangulation
stations based on a brig-line trtangufation
scheme but with shorler station-to-alation
distances established to provide more easily
available control of higher aocuracy to local
users.
danaltorrretar-An Inafrumant which Is used
for measuring fiihl (elfhar trsnsmlftad or
reflected) in terms of density tolerances.
Transmlsslon densitometers measure the full
density range 01 negatives and the reflection
densitornaler measures the reflectbn range
(density) of opaque coPy. A numbered scale or
digital display allows armxrate readinge of
specilk areas for comparisons or coniml
purposes.
cfenalty altltuda—(JCS) An atmospheric
density expressed in terms of the effitude which
corresponds wifh that density in fha Standard
Atmosphere.