PHOTOGRAPHIC RECTIFICATION BY IMAGE SCANNING

• Document Type: CREST
• Collection: NGA Records (Formerly NIMA)
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78B04747A000600080052-1
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 21
• Document Creation Date: December 28, 2016
• Document Release Date: February 8, 2002
• Sequence Number: 52
• Content Type: REPORT

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?11C-TOGRAPIIIC R'.:GTIFICJ\ TIC`N BY U' AC i, 'CANNINC
STATINTL
STATINTL
Abstract-
Declass Review by NIMA/DOD
IN any people concerned-ti4rith the rcctifi-lation of ohliq__,c 3hot.~,gra;7h}r
have been intere''ted in the application of iertr. in agfe acanni.ag for great-
er verzatility am n-ore general re^tifrin; transf_'rr
corrponents and techniques have
['he a3,-)roach to the probL
ation . _' dvanc; in
piques which, while united to otie typ
Tbi ~ req. irc_ the a_-,?lication of cathoP'.- ray
tubes for scanning since they are not l;irr:ite.r in the flying spot scanner deflection yoke. For oblique anti pano-
ra.c is rectifying transformations, it can be shuwn that Yr is constant for
any strip scan position (Yp0, :'p1, etc.) and that Xr = Xp where li is a
constant determined for any strip scan position (Yp0,
amplitude L. Xr varies continuously as an analog of lens position (X).
The position of the strip scan (reading lens) can be computed by inte-
grating the scan raise Xr from a previously known position. (The ratiu of
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vclociti s Xis constant for any strip scan for rectification of oblique
r
or panoramic images. ) i he accuracy of the computed position can bk in.-
arov-d if it is checked at precor,,pt:ted point; -r of Xrl, etc. when the pri?:t-
ing lens is at positions Xp0, Xpl, r.tc., resp_ctivcly.
The position of the negative plat(~.-i (Yr.. Yrl, YrL....) is depend-2'-It
only upon print table position (Yp,, Ypl, Y )Z, :tc. ). i hese positions can be
precomputed to command the position of t?h .Zegative for si:cce. live trip
scans. The accurate computation and control of -cans iiaa indicated the gee
of a n,.:rr:erical control ysten. sirn.ilar tc that employed for anton,atic contour
milling.
De sign
functional diagran of the photo rectifier is shown in Figure 4. The
photo transmission system eonsi:at of reading and printing flying spot scan-
ner3 and the video link. The scanning mechanism includes the synchronized
electronic sweeps and th precision lens drive and film indexing system...
The programming systerat continuously computes and commands the position
and velocity of scanning from numerical data on punched tape.
Photo Transmission System
The photo transmission system is basically a closed-loop television
system. The negative is read by a flying spot scanner (using a cathode ray
tube and a photomultiplier). A projection quality cathode ray tube is used
for reading. The video signal is displayed and the display is optically re-
duced on the photographic print. Less resolution is required for printing,
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in:e thc, r.:inin:u - nr_uat:' scal^ ,,nlarr?r.-cnt 1 ' 4'-. (~, 7^ .- z.' .zi^ryr3R;iv I
darted to a positive transaarency -1Z inch fiL_'..
h ~rz=.c~ a1 con.ileration in thr i~ho:o transmisr:ion deign .vas good
-jy the i n F>
o . ; pr. s .`h V
31'. tirln, :h' :R'22:r;z ra'y' s' 'vra _ 1'] ',aiiy re.V
'hr- r`::' -.r'r ..a 11^h~ Cath y.', r ._.r d .ham _r-:jai fi th.,
tl.!,,3Ai?r. Ac . ate it;.prevcr-int in light wa &chi-r i yhr--)t-h the ;28e
of a lar,- a7prt-r- -)rc:,j=.Ctir,n brig an-- by a s^anninry raster (a to a
line ra,_,,. on ':a_hEri' ray t=-.be. ra tmr :.cam red :cec, :h4:, 1hor fatirie
(fr,~r : rc;~_:ate . oana) and -3ern itteu ia?::r~?a:,e+j baan, cu.urrcnt. i.nc?, tha v:-er-
tii ai `..`r trip :scan iv .,rir-ari1j by ran-lating the leri-, :h- !-,,as n- Ition
an, `-elr-city were compen3ated to corrc? t fir tha raster .can.
;ve:;ial attentf?)n was al3v giv"an t~, filtering and the re :-lati^n of -3o"ver
c. cannin "Me chani z n;
The method of canning is ~hown in :"figure 4. Cathode ray ,-.-,be di .play..
are optically projact~-d for line canniz . The ?rojection lens 1 - traz' 3a:ed
to produce strip can ; and film 16 moved to cover a sqeq fence ai adjacent
car-tig n~us strip in-ages.
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_ine scant; ar, grria!rated frog- a common qw'ee.p voltaf e !!ea;rat-)r.
? srintiri ':i?_ ; )e .:creep is fixes, in am.pliti-.d and orientation.
linear r~ a.Thi zan i var-ied in aro 111[;s' and rotation by chit -iZi hr:rizcntal
an- vc:rti::al Cieil:;c ion coils with the zignal c' r:a?anent
cwcep aIr lit...,e c
a al ?; _ iiogllrlhl'? uricin v11 r.< a ~i t2iE r !SU. 2~i'7Zi.
. ri- can:-, ar _: Jr"e:' wing u:h 'iri.jectior: lens ~_arriage on a
._) i anc: ai ai. pain
h n i .,:1 h laa_i cr;-. vY- r: threa:1 l`~'I' 4'
ILLEGIB
r:cal ',;ontrol
the rrtethc. i of in 4 _)Ptlection
.ignalb at the pickup cathode ray t:he ar atten sated by taa i contro11L=1 atten-
-i.atorn consisting of relays and preci -icn re:3i.,tor 3. : ~nc de!fIn,-t.; hn c ry rzon-
ent is also atten gated a*= an analog of lens position.
The reading platen is positioned by a cr~~o syster . '"hi i.. accorr--
plished by corjiparing it m.:n;erically en;:-)de l position with program tape
comrrand..
To perform the image rectification, it is necessary to control the read-
ing lens position as a f='nction of the printer lens position at any instant in
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time. Figure 5 shows how the desired reading lens; position i = c~ntin::o. wly
o .p ted and regi3tered. At the instant the printin` 1en reache a startinC
_,r reference po~it.~n, the fie :fired numerical reading lens pc=: ition (for a
) cific .scan) i- read fry},+.i the taoe a?_1u regi'-tered in the reference 306ition
',,Inter.
a i%iUn ),;1=ce generator a j zl e for a min.;tc increment of ien:_
_s1)lace rent. A count of the=e o iL~r,r --.1 i; a ,reci>,e indicatiron of rti.q-
Aeiclrr?.ent and the p- L; :. rate i=, anaic O to the lens velocity.
;y _)rograrru:,Lng the ratio of strip scan velocity, a ?t:ise rate can e
orou.c- analoe-;., ro .he reading --can velocity. V his is accnr plirhe
r..~.:itiolying the frequency and iiviciing it with a 7rogran's Y..eo Co tit .r.
sftcr he initial tensicjbidon is rtsvistc,re i .iv a counter, each -lL. ,e o`s ready
velocity analog is added in the counter. 'h- -o ~ntcr continuo- ~ y regi tern
:ham i.t'teu n.tr ?.rival reading can p,3
my a minute error can rep:?.i f 'or-. the method rd con--outing ?,'lse
frequency, since only a finite number of v'loc_ity ratios can be noni ricall
progranxy.ned. In order to prevent the acc7..n? -..lation of a :3ignificant error,
the registered position in th:s co:.nter it, corrected from the or nc:held tape
data at frequent intervals (bettor than ?3 tines per inch of reader lens travel).
The reading len position is controlled by the reference counter indica-
tion. Figure 6 ?'hows the lens servomechanism. the lens position is nu-
merically encoded by integrating its pule rate velocity analog from an initial
reference position. The position is registered by a true position counter.
After comparing the commanded and. controlled positions, the numerical
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table high :a:~r1rn gain with nAnir- , c(=ntrc:l error.
~rcLici~ 3o.jition control. Acceleration and rate damping enable the of a
error is converted to a voltage, analog. The len.; velocity is deLLrrr in ed by
~?uted v,-locity analog with a -.crvo loop) an.i th.~ ._rr er _gn
h~ ?erforr.-anc of the
,''igure 11 a. i he rec-Lifi"d in-7age i8 :3hown in a eigure l b. i he orig i tal rectiii-
'l2u ;:~?ra`-)Ili. I n aerial sJhotogra;]h froL=1 a Jailora . is can wren ? -hC;wi in
)hotogra7hic re_i-lt_,. . be principal rc ;1' -: a , the. r , titicat nif pan_;rar;: c
gri !nii':ate thv nat'"'r = ')I ';h.: '.ctiiy'ins trans{'_7rr attar.
per 1 photographic line). (The method of measuring reading resolution was
which results in 40 photographic lines per rnillir_ieter (accepting 2 T.. V. lines
This rnea_+uren.ent showed that 2000 T.i . V. line, per inch were well re :.salved
rise time when scanning a eharp edge in the negative .)lane (a test reticule).
re:;olved.
The reading resolution was determined by r:'cac ring the video signal
or r.>Ceol.:tlon Chart in the negative fil-- ?gat and
he renult was further enlarged 5X in a'hote enlarger aid hown in rig i.re
4 . the I C and 32 line j er n.illirr:eter targot arc circle' :howl ; they were
verall iy-terin resolution wa- rr~A. = :r b:);,' placi.;,+r a tardar-i Air
taken from Reference 2.)
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~'he printing :;y. ten: re.3olution wal, meaa'1red by generating a dot pattern
on the printing brine :cope. Better than 20 photo line: per n-.illir: -~t:r w.r r
;c;1vcd on the -irinted '.attern. This correvnondcd to 130 line:-. ,er r illiz eter
with ; ti.~~eet to the negative sr_aic aft',r 1Y cnlar*enient. 'hotc'gra?h2 were
nlaro _ 4~`z ) at
(at the nadir 3E ~int e a < ?~ ~ir_r_ reciifie~i. Thi > t _ant
,.aally
re~:..cr _e (le,.eradation of image eieeta.il -,,r thee fir itat_ion in :orintine relolition.
t~os_ re halms
.e -,i =, )t:cai r?...ict,orz r-~< .:h..~-;f