very high resolution, high contrast and low speed, requiring 
longer exposure time (e.g. Kodak Panatomic-X 2412 or Agfa 
Aviphot Pan 50); 
-large-scale photography essentially flown at low altitudes and 
low aircraft speeds in poor light conditions (low sun altitude), 
normal-resolution black and white emulsion (e.g. Kodak Plus-X 
2402 or Agfa Aviphot Pan 100 or 150). 
Figure 2 illustrates the amount of image motion corrected for in 
the lens cones of RC20 / RC30 by the FMC device: 
ds=vh*c*t*10° [1] 
ds image motion (microns) 
v/h flying height (m) to speed (m/s) ratio 
C camera focal length (mm) 
t exposure time (s) 
Examples of typical parameters for large-scale photography are: 
image scale 1:5000 
flight speed V- 90 kts, 120 kts, 150 kts 
exposure time 1/200 s (max. 1/100 s) 
FMC is implemented since 1987 in the drive unit and in the f:4 
lens cones of the Leica cameras. Besides better image quality at 
all image scales, camera systems with FMC can be amortised in 
a much shorter time period due to it’s usefulness, in reduced or 
poor light conditions throughout the whole year. 
Image motion corrected by FMC 
Image scale 1:5000, exposure time 1/200 s 
80 
  
  
  
  
  
—--—--—*-—--—-6e—---—---ó 
703. 
60 EZ = Cz E 
50 
= A a — — — — A 
e 40 
= 
B. 30. 
20 
10 
0 
ck (mm) 88 E33 213 303 
flight speed (knots): 
— A —90 fT 1 2.0) -—- =150 
Figure2 
Effect of angular camera rotations 
Aerial photography flown at low altitudes in turbulent 
atmospheric conditions with small relatively unstable aircraft 
(single engine) and long exposure times causes blurred images 
in cameras without stabilization. The purpose of the newly 
introduced Leica PAV30 Gyro-stabilized camera mount is -in 
terms of image quality- to counteract by active means the image 
blur resulting from pitch, roll and yaw camera rotations during 
exposure time. 
Image blurring increases with the radial distance in the image 
plane and with the exposure time. 
ds (x) = t*[-W,*e(1+x"/c") + W,* xy/c + y* Wi] [2] 
ds (y) = t*[-W,*xy/e + W,*e(1+y"/c") - x* Wa] [3] 
ds(r) = [ds (x) * ds (y) ]^ [4] 
where: 
ds(X) image motion in x (flight direction, in microns) 
ds(y) image motion in y ((lateral direction, in microns) 
ds(r) resulting image motion (vector, in mm) 
t exposure time (s) 
C camera focal length (mm) 
X,y image coordinates (mm) 
W angular velocity in pitch, around y axis (mrad/s) 
W. angular velocity in roll, around x axis (mrad/s) 
Wa angular velocity in yaw (drift), around vertical (mrad/s) 
Figure 3 shows for typical large-scale 1:5000 photography the 
resulting image motion in the film plane at three radial 
distances (centre, at a radius of 100 mm and in the corner at 151 
mm), for exposure time 1/200 s and angular velocities of 2°/s 
(35 mrad/s) corresponding to a typical turbulence. It has been 
assumed that the three rotations pitch / roll / yaw occur 
simultaneously and added absolutely. 
  
Image motion from simultaneous camera 
rotations pitch, roll, drift (2°/s) 
120 
  
100 
60 + 
micron 
40 - 
  
  
c (mm) 
  
radial distance in image frame (mm): 
— A —0 —{ 100 — @— 151 
Figure 3 
Combined effects of forward motion and angular motion 
To illustrate the reduction of image quality caused by this 
effect, both above evaluated image blurs have been combined in 
Figure 4, using: 
[(FM)^ 4 (AMy]^ [5] 
as motion parameter. 
Image motion from combination of forward 
motion and simultaneous camera rotations 
  
  
  
  
  
= 
B 60 
e 
i 40 
| 20 
| 
0 1 = 
c(mm) 88 153 213 303 
forward motion mangular motion Dcombined 
-  Figue4 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996 
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