International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part BS. Istanbul 2004 
  
  
E Control p 
  
Figure 7 Mosaic of rectified photographs in the wall of the 
nave of St. Domingo de Silos’ Church (4mm 
GSD). Photographs taken with the 20 mm lens are 
also shown. Control and check point network is 
displayed. 
In this case, only one strip (10 parallel photographs plus two 
convergent ones) was processed. Camera stations were at 9.5 
m, as average, from the wall and the bases were 1-1.2 m, so 
the B/D ratios were near to 1/10. 
  
  
  
  
  
  
  
  
  
  
  
  
WALL A B 
rms XY +56 mm X52 mm 
max. Vxy (abs.) 69 mm 6.4 mm 
rms Z 79 mm +71 mm 
max Vz (abs.) 12.3 mm 13.8 mm 
Prop. Error (XY) 1:2500 1:2650 
Prop. Error (Z) 1:1200 1:1400 
Table3 . Wall case. A: rms and proportional errors in 
planimetry (XY) and depth (Z) at check points 
with the camera  pre-calibrated. Maximum 
residuals in XY and Z (in absolute values) are 
also expressed. B: rms and proportional errors in 
(XY) and (Z) at check points after field self 
calibration. 
Control, check and pass points were measured and, then, the 
strip triangulation was processed considering the camera 
calibrated at the laboratory conditions. Next, a new run with 
self calibration was carried out and inner parameters were 
also adjusted. The results are displayed in Table 3. In this 
table, the proportional errors in XY and Z are also expressed 
as rmsxy with respect to largest distance in the wall 
(approximately 14 m) and rmsz with respect to the camera- 
object distance (9.5 m). 
In case A (Table 3A) with the camera calibrated at 
laboratory, accuracy was similar to that of the vault case 
(mean errors below +8 mm). But, the field self calibration did 
not improve meaningfully the accuracy, just nearly 10 % in 
both XY and Z (Table 3B). In any case the final results met 
the accuracy requirements (+ 3 cm in coordinates and a final 
plotting scale of 1:50). Probably, the photogrammetric 
network in this case was not strong enough to solve 
adequately the self calibration. 
4.3 Comparison of UMK stereopairs and analytical 
plotter with Canon D30 in the study of a facade 
Finally, another usual situation in architectural 
photogrammetry has been tested. In this case, single Canon 
D30 stereopairs have been oriented and the results have been 
compared to those obtained with a metric camera (UMK 
1318/10) and analytical stereoplotter (Leica SD-2000), 
(Figure 8). 
  
Figure 8 Two UMK 1318/10 stereopairs (above) and two 
Canon D30, with 20 mm lens (below), in the 
façade of St. Domingo de Silos’ Church. 
The church façade was photographed with the UMK and two 
stereopairs were taken. Usual 1/5 B/D ratios were employed 
and the photo scales were approximately 1:100. The 
orientations were made with 12 parallax points per model 
(distributed as usual in six areas), 4 control points per model 
and a total of 8 check points. Table 4 displays a resume of 
the accuracy obtained in both UMK stereopairs. Errors are 
better than + 5 mm. These errors were the expected with 
these data acquisition and reduction methods since the 
control point were well defined but natural points. The 
orientation errors with the Canon D30 were compared with 
these data. 
Stereopairs with the Canon D30 were taken with same 
conditions. All points were manually measured and a bundle 
adjustment was performed. But orientations were computed 
in six different ways. First, the models were solved same as 
the UMK stereo pairs by using the field control points 
(Canon D30 CP in Table 4). Although accuracy has been 
poorer than in the UMK case (as expected), good results 
were obtained with mean errors better than + 1 cm. In this 
case the camera was considered as calibrated (with data of 
Table 1) since self calibration was not possible in single 
stereopairs. 
A second choice was selected since it is usual the lack of 
control points in fast and low cost surveys. In this case 
stereopairs were oriented with a known distance (DIST in 
Table 4) and three selected points for datum definition 
(Atkinson, 1996). 
  
     
    
   
   
    
  
  
   
   
   
   
    
  
  
  
   
   
  
   
    
   
   
   
     
    
   
    
   
    
   
    
     
   
   
   
   
   
   
   
    
     
    
    
    
    
  
    
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