1 - NGA

I
,., . . MIL-HDBK-B50
contour eketctstng-Freehand definealion of
the wrtece refiif on a map as seen in
PSr6P@~e view, WI COmmll@ by bcations on
the rnaIz corresooncthm to salienf rninfs on the
ground’. -
COntOUr walue-A numerical value placed
upon a czmfour tine to denote ifs alevation
refetiva 10 a given datum. usually mean sea
level.
contour-An imaginary fine on the ground, all
points of which are at the same elevation above
or below e apecitied datum surface, usually
mean sea level.
contract-(pholooraphy) The adual ddfarence
In densffy between the higfrti~hts and the
shadows on a nagafffe or positive. Contrast is
not mrtcemed WISII me magnitude ot density,
bul only with the difference in densttiee. Also,
the rating of a pholographt material
corresponding to the relative density difference
which if exhibiis. See also characterlatlc
curve; density, definition 1.
control berse-A surface upon which the map
projection and ground control are p!dted and
upon which templales have been assembled or
aarolriangulation has Imen accomplished and
the control poims thus determined have been
marked.
Control data card—A card containing
poshional data and descriptions of individual
horizontal and/or vetiisal control points, Also
~sl~d geodotlc data street. See also trig
control tllght—See control strip.
COntrOl marking—A note or other term of
caveal shown on an MC&G product indicating a
need for special handllng and tor controlled
dissemination.
control net—See aunrey net,
control pohrt photography— Electronically
mnfrollad aerial photography mnslsling of four
flight lines fbwn in a cloverleaf pattern from the
four cardhal diredions and with the filghls
intersecting over a target or secondary mmrol
point.
COntrOl point— 1. Any station of known
Coordlnales in a horizontal or vertical confrot
network that Is identified in a data sel or
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photograph and used for cwrelating the other
statkon data The term is uaualfy mortified to
retlect the type or purpose, such es ground
control point, horizontal control polm,
photocontrol point, picture control
point, and vertlcel control point. See also
control station; secondary control point;
aupplamantal control point. 2. (JCS) A
point located by ground suffey with which a
rnrresponding point on a photograph is
matched, as a check, in making moeaics.
control station-An obIed or mark on tha
grouti of known poeifikzn or alevatkon, or both,
in e network 01 ground corrtml, Control stafiins
constitute the tramework by wh!ch map detalfs
are fixad In their correct positbn, azlmufh,
elevation, and scale with respect to the Eerlh’s
surface. Also called ground control point.
See also control point. ‘
control atrlp-(aerial photography) A strip of
aarial photographs taken to aid in planning and
accomplishing later aerial photography, or to
serve as control in assernbting other strips. Also
called control flight; tie flight; lle strip.
See elSO crose-fllght photography.
control eurvey cleeelrlcatlon-A aeties of
designations 10 classily control surveys
according to their tield survey methods and
accuracy, The highesl prescribed order of
control survays is designated first ordar; Ihe naxr
lower prescribed classlficalion, second order;
etc.
control survsy-A survey which provides
positiine (horizontal acd vertical) ot poinls to
which aupplememary surveys are adjusted. The
fundamental axrtrol survey of the United States
provides the gaographc positions and plane
coordinate of triangulation and traverse
stations and the elevation of bench make
which are used as the bases for hydrographies
surveys of the coastal waters, for the control of
the topographic survey ot the Unhed States,
and for the control of many state, city, and
prlvale surveys.
control-atatlon ldentlflcatlon—See
photoldentlflcatlon.
controlled map-(JCS) A map with precise
horizontal and verl!!al ground control ae a basis.
Scale, azimuth, and elevations are accurate,
See also map.
controlled mosaic—(JCS) A mosaic