1 - NGA

prlrrclpd 8tatlon-See main schema
station.
princlpd vorflcai circla-l%e veti”=l circle
through the north and rmulh points of the
horixon, ccirrcidmg whh the celestial meridiin.
prlnclprd veMcal-(JCS) On an oblique
photograph, a line psrperrdiiulsr to the trua
horizon and passing through lha principal point.
prlrrclpd-dlst~nco ●rror-in a stereepletting
system, an instmrrwmt error resulting from
iW~r ~lamtbn d the aeriel csmere,
diie printer, er pmjactw. The error is d
I little impcxtance in a flat autfa~ ~~ ~ the
I
I
MIL-HDBK-850
effects era incrassd
the model.
in prcportien to the relief in
prirrclpal-point assumption-lhe
asaurnptkm with respect to appmxirnstefy
vatiical DMefysfis tfwt radiil directiane are
cmract fi *U* fmm the principsl peint.
principal-point ●rror-A personal error in
wfrich the principal peints in a stereoplotting
+ystem are dspbced in such e rrrsnner that
they have unsqusl x componems with a
resultant error in vert”~l acsla. Such ermffi are
ususliy irrfrcducad into the system by either
irrrpmper ~“entstbn of the d~pcsitwe plste in
ths printer, in the prejecror, or both.
prlnclpal-polrrt radial-A radml from the
principal pekrt of a photograph.
prlrrclpal-point triangulation—See radial
triangulation.
print-A photogrsphw copy msda by projacrion
or contact printing from a nagative or
transparency. See 81s0 contact print:
dlapoaitlvc; ●nlargomsnt: matto print:
photographic raductlon; pro]ectlon print;
ratio print; rtrctlfled print; transformed
print.
prlamatlc ●strelaba-An astrolabe consisting
of a telsacope in e horizontal position, with a
prism and arfifiiisl horizon ❑ttached at its
objective end, uaad for detemnining astronomic
positions.
prlamstlc compaae-A small msgnetic
~v* h?kf in the .harrd whwn in u6e ad
aqwppad wffh psep.wghls and glass prism no
202
arranged that ths rrqrnatic bearing or sximuth
of a lie can be resd at ths same tima that the
Iina is Sightad over.
prlarnatlc ●rror-lhef error due 10 lack of
persflelbm d the two faces of an optical
eJenrerrt. erMresa mhrorora .shsdagle se.
prtarn-A transparent body bounded in pt by
* pkm!3 faces thst ara rmt Pruwlbh used to
deviate or dbparaa 8 bsenr of light. S8s also
dova prlam; horizon prlarn lndax prism;
Porro prlam; roflecthrg prism; refracting
prism; ratrodlroetlve prism; rhomboidal
prism; right-engle prlam; roof prtnm:
wedge.
Probeblllstlc Vertical Obatructlon Date
(PVOD~ file whd cOrnbineC M6kjUd
dansify functiens with discrete varticsl
ebstructien dsta extrscted f~m v~~l
Ohtruction Data (VOD), Digital Festure Anefyais
Dats (DFAD), the DhAA Digital Verticsl
Obstruct”on t% (DVOF), Powerfh Data, and
intelligence dstsbssss. PVOD provides cruias
missile and aircrsft missien plannsra verticsl
obstruction inferrnatien which csn be used to
rnmpule probability. el mission ~ss, set
mean cbsrsnce heights, ad plan mission
mules. PVOD is the repbcement product for
VOD.
probability hrterval—See confidmce
interval.
probable swror—1. In B measured valua, if is
the moat probable value of the resultant error in
the measurement. This is a plus or minus
qusrrtity thst may be Iargar than lha resutranl
armr or srnallar than the reeuftant arrcr, and ifa
prc&3bility of bahg larger k squat to its
prebsbifiiy of being smaller. 2. The 50 parcent
error interval based on the bwariate normal
distribution function.
procosa camera—Sea copy camara.
process color prlnlln~lithography) A
Iechn”que tor the reprcductien of a subjsct or
chsfl in full cetor rendifiin, by cerrrbining tones
ef the primsry cobrs, (yelbw, msgtmta, cyan)
and bbck. Sea also procaaa plates.
procasa lerre-A lens for photechemical
~pyln9$ enIar9in9$ or projsct~n pumcaea, free
fmm aberratbns, usually of low aparfure and of
eymmatrid cunafruclion.