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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
  
oom | 
Ortophotograph (3 mm GSD) of the rib vault of St. 
Domingo de Silos’ Church (XIV" century, Spain). 
Control and check point networks are shown. 
Figure 5. 
Final results are shown in Table 2. Table 2A contains the errors 
in planimetry (XY) and depth (Z) when the camera Canon is 
considered as calibrated and the inner parameters obtained in 
laboratory (Table 1) are fixed. The table also expresses the 
proportional errors in XY (rmsxy with respect to the vault 
diagonal, 9.3 m) and Z (rmsz with respect to the mean object- 
camera distance, approximately 6.5 m). Table 2 shows very 
promising results about the accuracy obtained (errors, 
expressed as rms, below +6 mm). 
In order to check out any improvement in the results, a field 
self calibration was run and new inner parameters were 
computed. As can be seen in Table 2B, the results were 
improved, in particular the Z (depth) coordinate. Thus, while 
/ 
the accuracy in XY improved only 12 %, there was an 
important improvement of accuracy in Z of 40%. 
  
  
  
  
  
  
  
  
  
  
  
  
VAULT A B 
Rms XY +51 mn +45 mm 
Max. Vxy (abs.) 79 mm 6.1 mm 
Rms Z +6.0 mm X35 mm 
Max Vz (abs.) 119 mm 6.0 mm 
Prop. Error (XY) 1:1800 1:2100 
Prop. Error (Z) 1:1100 1:1850 
Table 2. Vault case. A: root mean square (rms) and 
proportional errors in planimetry (XY) and depth 
(Z) at check points with the camera calibrated at 
laboratory (inner data in table 1). 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. 
Although the photographs were not convergent (in fact they 
were parallel shots), relatively good conditions to apply self 
calibration occurred: large depth differences in the object 
(between 3.5 to 7 m); high overlapping photographs; high 
redundancy; and the measured points (control, check and pass 
points) were well distributed in all frames. 
Finally, inner parameters were imported in a DPW (Socet Set© 
v.4.4.2) and a DSM and ortophotograph were produced. Cross 
sections were derived from the DSM and the vault deformation 
was analysed (see Mata et al., this volume). 
4.2.2 Wall. Next example illustrates the photogrammetric 
survey of a side wall in the nave of St. Domingo de Silos’ 
Church (Figure 7). Some stereopairs were taken. Two 
additional convergent shots were made to complete the final 
mosaic of rectified images, because there were hidden areas 
behind the pillars of the nave arches. 
  
Figure 6. Block of zenithal photographs (Canon D30 with Sigma 20 mm lens) in the vault of St. Domingo de Silos” Church.