Dean Merchant 
  
  
  
  
3.3.1 LOW-ALTITUDE INVESTIGATION 
Results of the low altitude investigation shown in Tab 
determined by GPS to those determined by single phot 
For details see Merchant [1996]. 
le 1. are in terms of comparisons of exposure station coordinates 
o resection (SPR) based on in situ and on laboratory calibrations. 
  
  
  
  
  
  
  
  
  
  
  
  
  
EAST NORTH UP 
in situ lab in situ lab in situ lab 
bias 0.033 0.045 -0.015 -0.028 0.004 1.671 
std. dev. | about 0.064 0.094 0.038 0.105 0.051 0.044 
mean 
std. dev. | about 0.073 0.106 0.041 0.109 0.051 1.805 
GPS 
  
  
Table 1. Coordinate Discrepancies Between GPS and Single 
Photo Resections Based on In Situ and Laboratory 
Calibrations for Seven Photos at 1245 Meters Above the Ground [meters] 
3.3.2 MID-ALTITUDE INVESTIGATION 
The same aircraft and camera system were next flown over the mid-altitude range . Results of exposure station 
comparisons are shown in Table 2. For details, see Merchant [1997]. 
  
  
  
  
  
  
  
  
  
  
EAST NORTH UP 
in situ lab in situ lab in situ lab 
bias 0.125 0.096 0.015 0.016 -0.005 1.417 
std. dev. | about 0.148 0.152 0.177 0.185 0.065 0.073 
mean 
std. dev. | about 0.198 0.183 0.177 0.186 0.065 1.505 
GPS 
  
  
  
  
  
  
Table 2. Coordinate Discrepancies Between GPS and Single-Photo Resection Based on /n Situ and Laboratory 
Calibrations for Nine Photos at 3070 Meters Above Ground [meters] 
3.4 NATIONAL GEODETIC SURVEY EXPERIENCE [NGS] 
The NGS of the National Ocean and Atmosphere Agency [NOAA] has also conducted in situ calibration tests in 
cooperation with the United States Geological Survey [USGS]. See Merchant (1995). In this case, a pressurized twin 
jet Cessna Citation aircraft and a Wild RC-20 15/23 camera were used. This aircraft is pictured in Figure 2. 
For this experiment, the aircraft was flown at 5800 meters above the ground and cabin pressure was maintained 
equivalent to that of 2000 meters. Between 10 and 14 widely spaced target images appear on each photo. Results of 
comparisons of exposure station coordinates is provided in Table 3. 
  
  
  
  
  
574 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 
  
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