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Proceedings of the Symposium on Progress in Data Processing and Analysis

3- Minimizing influences due to aircraft movement
Only two of the movement components have a significant
effect on image quality: forward motion of the aircraft,
and angular oscillations excited mainly by air turbulences.
The influence of forward motion is known, and the use of
aerial survey cameras without forward motion compensation
(FMC) is declining. Due to the angular motions, photogra
phic system with FMC (such as LMK, MKF-6, and MSK-4) cannot
yet completely dispense with a limitation of the long
exposure times. This limitation, however, is subject to
factors differing from those limiting forward movement. For
identical angular motions, it is independent of the flying
height. The effect of angular aircraft oscillations on the
image data has bean analysed according to /3/.
The typical angular motion frequencies having the highest
effect on the image range from 0.1 to 1 Hz; the amplitudes
of their angular velocities exhibit a significant depen
dence on turbulence. Under smooth flying conditions (with
out noticeable turbulences), the roll motion of aircraft
with take-off weights of 3...6 t and without autopilot
system reaches angular velocity amplitudes of up to l°/s,
while in the presence of medium-scale turbulences the maxi
mum is 4 °/s. The pitch and yaw amplitudes are 20... 30 */. of
the above values.
Fig. 1:
Determination of the
total image point mo
tion for different ima
ge coordinates.
Example: LHK-15 at
medium turbulence =
3 ° /s, Ï = * = l°/5l
and shutter speed t fi =
1/350 s, or mith scar
cely noticable turbu
lence (w* 1°/e, *î°=3c“=
0,4*75 and t 8 = 1/120 s;
drift has been compen
sated i .e. <#0 - 0° ;
cf ,Û?,¿maxima in phase;
co in the image repre
sents A bUùj) etc.
The figures are amounts
of image motion in /im .
Locations in the image
frame are designated
according to orienta
tion in the aircraft.
Contrary to roll the other angular components, pitch and
yaw, add only about 25 '/. to the maximum
Depending on the phase relation of the
nents produces a maximum of image point
least at one point at the frame edge of
of the four corners. An example of this
total image motion.
individual compo-
motion (bluring) at
the image or at one
is shown in Fig. 1,