.OPY 
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analyti- 
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end of 
The 65 
00 ata 
resolution of 12.5 microns resulting in image files con- 
taining approximately 17,800 lines by 17,800 samples. 
The diapositives were also scanned with the Intergraph 
PS1, at resolution 15 microns, resulting in  approxi- 
mately 15,340 lines by 15,340 samples. These images 
are being used for an experiment with Intergraph that is 
still underway. : 
The positions of the 263 pugs on the images, as well as 
positions of pass points, were measured automatically 
using the Leica DPW 770. These measurements were 
carried out by the Leica staff. 
Leica was asked to measure the location of the pugs but 
not to include these measurements in the solution of the 
AT. This is to avoid incorporating in the adjustment 
the skill of the human operator, whose stereoscopic 
vision determined the conjugate locations of these 
pug points. Using the AT output, ground coordinates of 
the pug points were calculated. They served as check 
points, by comparing them with their corresponding 
values, generated earlier with the conventional ap- 
proach. 
The WisDOT also supplied a DTM of 5 model subset of 
the strip. Points and break lines were collected manu- 
ally using Kern DSR-14 analytical plotter. A file with 
23,799 ground coordinates was produced. 
A surface covering approximately the same area was 
generated automatically at regular intervals using the 
DPW 770, resulting in digital elevation model (DEM) 
files. Since the DTM points were not extracted at a 
regular interval, the corresponding points from the 
DEM had to be interpolated for meaningful comparison. 
3. EXPERIMENTS AND RESULTS 
3.1 Aerial Triangulation 
AT files provided by WisDOT contained coordinates (X, 
Y and Z) of each of the pug points. These values were 
calculated using a WisDOT in-house AT procedure. 
These coordinates were compared to the corresponding 
values generated by each of the softcopy systems. The 
comparison results are listed in Table 1. 
Table 1. A Comparison of the differences between the 
ground coordinates of pug points determined by con- 
ventional methods and the values determined by Leica. 
  
  
    
   
   
  
  
  
  
  
  
  
  
X Y 2 
Average Difference (m) 0.01 -0.00 0.09 
Variance (m) 0.078 0.084 0.049 
S.D. of Difference (m) 0.01 0.01 0.22 
RMS Difference (m) 0.08 0.08 0.24 
  
341 
Figure 1 is a plot of the deviations in Z between the 
Leica derived AT values and the values supplied by 
WisDOT. The differences are relatively small, but there 
are few points with deviations greater than 0.5 meter. 
  
   
   
   
  
  
  
  
a 10 
o 
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= 
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= 
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ss ps ES ss ss NS ps 
EASTING (m) 
Figure 1. Differences in Z between WisDOT and Leica, 
calculated by AT, as a function of Easting along the 
strip. 
The corresponding deviations in X (Easting) and Y 
(Northing) was also plotted as a function of Easting. 
These charts can be found in Figures 2 and 3. Examin- 
ing the Figures 1 through 3, we can see that the devia- 
tions in X and Y are smaller than the deviations in Z. 
  
  
  
0.400 
t 0.300 
X 0.200 
= 
0.100 
S 
"S5 0.000 
> 
o 
Q 0.100 
0.200 
en © - «e © e =~ 
Y «o «o eo es en © 
wu en Q «e qe © uo 
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m Pre Pre Pre Pre m m 
EASTING (m) 
Figure 2. Difference in X (Easting) between the Wis- 
DOT and Leica AT values, as a function of Easting 
along the strip. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996