Commission VII
Presented paper 1
The Use of Colour Sensitive Films in Aerial
Photography in U.S.S.R.
by V. Y. MIKHAILOV
I. Aerial photography.
U.S.S.R.
1. Colour pictures have come to be widely used in the U.S.S.R.
In aerial surveying two types of negative film are employed at present: the three-layer
film enabling the image to be obtained in colours closely resembling those of the objects
recorded, and the two-layer, or spectrozonal, film producing an image in arbitrary,
500
300 400 500
700 M4
Fig. 1. Spectral sensitivity of
the CN-film.
speed of this film exceeds
contrasting colours which greatly facilitates the
interpretation of a variety of detail. The former
(designated as CN) has the usual structure of its
kind; its spectral characteristic curve is shown in
Fig. 1. The sensitivity of the CN-1 film formerly used
was the same as that of black-and-white film of 15
DIN; it is being superseded by the CN-3 film whose
speed is 20 DIN (70 unit of GOST as a minimum !))
and Gamma (y) approximating 1.0.
The spectrozonal film (SN-2) is made of two lay-
ers only, the sensitation maximum of the lower one,
which is panchromatic, being reached at 4 — 650 mu,
while that of the upper, which is infrachromatic, is
attained at à = 735 mu. (Fig. 2.) There is no yellow
layer between them, so the use of a yellow or orange-
coloured filter becomes a must when taking photo-
graphs. Upon development the upper layer shows
light-blue and the lower is rendered magenta. The
that of the CN-3 about 50-100 per cent, and its Gamma (y) is 2.0.
Owing to vast territories of wooded land being surveyed in the U.S.S.R. the SN-2 film is
more widely used as com-
pared with the CN film.
Experience has shown that
pictures taken on the SN
film, ie. those obtained in
arbitrary colours, make the
identification of a variety of
detail much easier; more-
over, since light filters may
be employed, it is possible to
take photographs from con-
siderably higher altitudes. In
this connection research is
being made on the feasibili-
ty of using other spectro-
zonal films with different
spectral characteristics and with a different distrib
& Ia
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—— — RA MÀ
T7
——— M—— o o—
LL —— —d4-——-—4
ÉL—-—-
— —— — — o Ro 7 —— ——4
1) GOST — National Standards of U.S.S.R.
500 500 700
Fig. 2. Spectral sensitivity of the SN-film.
ution of colour-forming components [1].