International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
  
2. SURVEYING 
2.1 Introduction 
Survey works were carried out for obtaining the ground plan of 
the church and the control points for the photogrammetric 
surveying (Figure 2). These works were the design, 
measurement and data reduction of the traverse and the 
measurement of plan church points and control points. 
2.2 Measurement and data reduction 
The traverse network was defined by 14 stations, both in 
exterior and inside of the church (Figure 2). All traverse 
stations were set permanent for further use in restoration works. 
Moinot method and forced centring were used. Least square 
adjustment was employed for obtain final station coordinates. 
The planimetric definition of the ground plan was obtained by 
means of points measured at the base of the church walls. 
SACRISTY 
   
OUTER WALLS 
  
Figure 2. Church ground plan and traverse scheme. 
Photogrammetric control and check points were measured both 
in face left and face right. More than 300 control/check points 
were measured with a Leica total station reflectorless 
measurement. These points were natural points selected in field 
in the original digital images. Examples of theses points are 
shown in Figure 3. 
    
  
Figure 3. Details of natural control points. Photograph shows an 
inner wall in the main chapel. 
3. PHOTOGRAMMETRIC SURVEYING 
3.1 Introduction 
Diverse photogrammetric instruments and methods have been 
applied since a wide variety of conditions were found. 
Instruments were: terrestrial metric, semi-metric and non metric 
cameras (analogical and digital); both photogrammetric and 
desktop scanners; analytical and digital plotters. Stereoscopic 
pairs and convergent photographs were used. Data reduction 
was made with conventional stereoplotters, analytical 
rectification and usual image processing software. The overall 
accuracy of the photogrammetric survey was better than 3 cm. 
In the case of rectified photographs, this accuracy concern to 
points in the rectification surfaces. 
3.2 Data acquisition 
Main eastern external walls and the fagade were plotted using 
analytical — stereophotogrammetry with UMK 1318/10 
photographs. When necessary, shots were made from a mobile 
hoist (Figure 4). Stereoscopic base lines were situated with a 
total station and heights were measured with a tape from the 
platform. 
  
  
Figure 4. Stereopairs in the west walls were taken with the help 
of a mobile hoist. 
The belfry, 17 m height, vault and inner walls were 
photographed with different cameras, both semi-metric (reseau 
plate) and non metric, analogue and digital, cameras: 
Hasselblad 500 C/M with a Carl Zeiss 80/2.8 lens (with a 
25x25 reseau plate installed); Pentax 67 II with Pentax 4/45 and 
4/200 lenses; and a digital Canon D30 (3.2 MP) with Sigma 20 
mm and Canon 35 mm lenses. 
These cameras were used in both normal and convergent cases. 
Convergent photographs were taken in order to reach a 
favourable geometry for bundle adjustment (selfcalibration) and 
control point densification, and also when the object/camera 
distances were limited. In some cases, stereopairs with these 
cameras (without orientation devices) were taken with the help 
of a steel tool (installed on conventional photograph tripods) 
which allowed for stereoscopic shots (Figure 5). 
    
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