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high denelty tops (HDT, HDDT)- A n
anafog racordtng Orrd pleyback system for
6tOring very high rale data that Is not directly
compatible whh general purpose mmputer
systems. Lfsed by CIMA for source imagery
under Digiial PmducIion Syalem production.
Afao known as high density digital tape because
the source imagery is Irarwlerred as digital data.
high rod-See long rod.
high tlda-See high water.
high water (HW)--The highest limit of the
surlace wafer Ieval raached by the rising tide.
High waler Is caused by the astronomic tideproducing
forces andror the effects of
meteorological conditions. Also called hlg h
tide.
high weter full and change (HWF&C)—
See eatabllahment of the port.
htgh water lntervel—See Iunkldel
Intervel.
high water lhra-The line on lhe bank or
shore to which the waters normally rise at high
water. In tidal walers, the high water line is. in
strictness, the {nrersect(on ot the plane of ttra
mean high water with ttse shore. The high waler
lin@ is the boundary line between the bed and
the bank of a stream.
high water Iurtltldal Interval-See
Iunltldal Interval.
high water springs—Sae mean high
water sprlnge.
high-obllque photograph—See oblique
elr photograph.
higher Mgh WatOr (HHW)-The higher 01
two hfgh waters occurring durfng a tidal day
where the tide exhibis mixed characteristics.
frlgher high water Interval (HHWl)-The
Interval o! time between the transit (upper or
tower) of the Mmn over the local or Greenwich
martdlan ati the nexl higher high water. This
expression Is use when there is considerable
diurnal inequality. See also hmlt1d81 Interval.
higher low weter (HLW)-The higher of two
low watem of a tktal day where the tide exhibits
MIL-HDBK-850
mixad characfarisiics.
higher low water Interval (HLWl)-The
inteWai 0[ tiMe betWEen the lriUWil (u~r or
tower] Of the Moon over Ihe focal or Greenwich
meridian and the nest h~her ~, waler. This
expression is used when there is C.ons”dersble
diurnal inequality. See also Iunlttda) MWmusJ.
hlgheat elevatlon-That elevafkm whlcfr la
the h~hest point of relief within Ihe area of a
map or chart. See also critical elevatlon.
high-(JCS) A height between 25,000 and
50,000 feet.
hill plene-lhe plane containing the posifiins
of three ground marks constffuting control
points. This may be, buf rarely is, a hOtizOmal
plane.
hill ahadlng-(JCS) A method of representing
refief on a map by sfepicfing the ShadOw5 that
would ba cast by high gruund if t!!ht were
shining fmm a cerlahr direction, Also calted
hlllwork. See also sheded rellef.
hltlwork-See hill shasflng..,
hlStOrlCSd ctrart-A chart based on data from
previous years 10 determine probable
oceanographic palterns for a specified time.
Also called flref approximation chert.
hletory overlay—A specially prepared matte
plaatic material which shows the sources of all
sounding dala used in a bathymetric
compilation.
holldey-(JCS) An urrinlentional omission in
imagery coverage of an area. See also gap.
hologrammetry—lhe arl or science of
interpreting the threedimensbnal holographic
image and obtaining reliable measurement by
means of hobgraphy.
hologram—The hologram offers a
reconstnr~ton of the ax femal appearance of an
object with unique threedirnensional propart’km.
This is accomplished by illuminating Ihe object
with coherent light.
hornogeneoue area-An area which has
uniform radar reflecting p9wer at all points.
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homogeneous eurtace area-A grouping