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Aircraft (Question 2). The 20 manufacturers and 38 models show the pos- 
sibility of a large range of vibration spectrums. This ties in with the 
facts that 14 respondees reported vibration as negligible while six con- 
sidered that it affects image quality. Carman's study will show the 
vibration characteristics of certain aircraft, but combinations of vib- 
ration spectrums with the range of camera mounts and cameras is too 
extensive to be covered completely at this time. 
Temperature/Pressure (Questions 3-7). The function of mapping cameras is 
to acquire quality imagery on film of a geometric accuracy capable of 
producing all types of maps. This implies that the calibration data of 
the camera can be applied without correction and that the imagery quality 
tests, resolution, acutance, or modulation transfer function are the measure 
of quality of the operating camera. Since any type of measurement varies 
with the condition of measurement, the equipment and procedures of camera 
calibration are carefully controlled. The elements of interior orientation 
as reported in the Camera Calibration Certificate are precisely applicable 
only under those controls. This does not mean that there is a wide range 
of environments where the certified values do not apply. It is obvious 
from present map accuraciés that good work has been done. Nevertheless, 
better image quality, which means cleaner edges and more accurate re- 
production of the target, is obtainable of the effects of the environ- 
ment could be known in measurable quantities so that individual surveys 
could be planned to avoid the problems. There is obviously no simple 
solution in the real world of surveying where the present trend is toward 
accuracy of microns-nonometers; but an understanding of the degrading 
effects of particular flight conditions will provide the surveying photo- 
grapher with knowledge to make significant modifications to his flight 
procedure. It is easy to see that a camera exposed abruptly to the cold 
of 30,000 feet will suffer a temperature shock. The ARDC Model Atmosphere 
shows the change from 20°C to -44°C, a 64°C difference. For this change 
a six inch piece of steel will shrink by 0.0043" (0.109 mm) and a six 
inch piece of glass by 0.0031" (.080 mm). Simultaneously the distortion 
characteristics of the lens will change due to temperature and pressure, 
and as shown by Meier, this is the function of lens design. 
Temperature changes that affect metal will of course, also change 
distances between fiducials and probably the angle. The abrupt change 
of temperature that occurs make it impossible to attain equilibrium 
throughout the camera and could result in temporary distortions of the 
lens cone. 
Glass has a lower coefficient of expansion than steel, but a change of 
309C will expand or contract the distance between two reseau marks which 
were 100 mm apart at the laboratory temperature, by 24 microns. Further, 
when the temperature change is rapid the scale change over the reseau 
pattern is not likely to be uniform. 
Recommendations: 
  
WG-3 expects to compile a list of guidelines for controlling or adjusting 
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