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The Environments Which Affect Camera Image Characteristics 
The environments which vary the basic quality of aerial cameras, as 
treated in this study, are vibration, temperature, and pressure. Vi- 
bration may be treated as a periodic sine wave, having a frequency 
range, with resonance points which are a function of the mass and 
Center of gravity, and an amplitude that varies with the frequency. 
Depending on whether the camera is mounted sclidly with the aircraft 
or to an intermediate mount which is designed to suppress the air- 
craft vibrations, the camera itself vibrates. Carman has shown how 
the actual wave form of the vibration may be recorded and he uses 
exposure time to segment the wave and evaluate resolution loss. 
One can expect the wave form (frequency and amplitude) to vary with 
the combination of camera, mount, and aircraft. Superimposed will 
be the random wave effects of turbulance, pitch, roll, and yaw. 
Image degradation is the result of an angular change, a bluring 
of the image, which occurs during the exposure time. 
This may be compared to the resolution loss due to image motion, 
computed as the ratio of ground speed times the focal length and 
divided by altitude. In both cases, vibration and image motion, the 
best control may be the shortest exposure time. 
Vibration affects all aerial cameras, reconnaissance and mapping, and 
its affect is greater as the focal length of the lens increases. 
Temperature changes the size of objects, or the distance between two 
parts of the same object, each material having its individual coefficient 
of expansion. The affect on a camera is to change focus and the dis- 
tance between fiducials. Changes in temperature and pressure result 
in different indices of the atmosphere. These act to change focal 
distances and the position of images, in effect, a variance of princi- 
pal distance and distortion in mapping cameras. (See Meier for de- 
tailed discussion). 
Mathematical corrections are possible provided the true conditions are 
known. Unfortunately, the conditions are complex and difficult to moni- 
tor and each camera type will respond differently. A list of pre- 
cautions may be the best guide.