LOW-HEIGHT AERIAL IMAGERY AND DIGITAL PHOTOGRAMMETRICAL 
PROCESSING FOR ARCHAEOLOGICAL MAPPING 
G. Bitelli *, V. A. Girelli, M. A. Tini, L. Vittuari 
DISTART, University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy 
(gabriele.bitelli, valentina.girelli, mariaalessandra.tini, luca.vittuari)@mail.ing.unibo.it 
KEYWORDS: Photogrammetry, Archaeology, Cultural Heritage, DSM/DTM, Orthoimage, Matching, Aerial photogrammetry 
ABSTRACT: 
In the framework of the Joint Archaeological Mission of the Universities of Bologna and Lecce at the ancient town of Soknopaiou 
Nesos (Fayyum, Egypt) a wide-range of geomatic methodologies were experimented (GPS, total station surveys, low-height aerial 
and close-range photogrammetry, Visual Reality, high resolution satellite imagery, etc.). The surveys were conducted with the aim of 
recording metrical and non-metrical information inside a common reference system for the development of a GIS for the 
archaeological area. 
The paper deals in particular with the acquisition and processing of low-height aerial imagery to provide very large-scale mapping of 
the area in support of archaeological researches. A remote controlled system, ad hoc developed for cultural heritage applications, 
permits to operate both semi-metric and non-metric cameras, lifted by balloon or kites with specific arrangements, in order to 
systematically take pictures over the study area. 
The images acquired during the 2002 campaign by a non-metrical camera, calibrated by field calibration procedure, were processed 
within a Socet Set digital photogrammetric workstation: acro-triangulation, digital orthoimage generation and mosaicing were 
realized. The external orientation was established through kinematic GPS-derived ground control points, surveyed within the 
International Terrestrial Reference Frame ITRF2000; the same kinematic survey provided also a DTM for the entire site. 
After a description of the overall approach to the survey of the site by the integration of different techniques, the paper describes the 
results obtained by this photogrammetric campaign, pointing out specifically the aspects concerning the non-standard image 
arrangement within the photogrammetric block, the problems arised by the geometrical structure of the buildings (e.g. the presence of 
very high mud-bricks walls in the temenos), and the use and comparison of DTMs derived from image-matching techniques or from 
GPS surveys. 
I. INTRODUCTION 
The ancient town of Soknopaiou Nesos (Figure 1), dating back 
to the Greco-Roman period, is located in Fayyum, Egypt, 
northward of Birket Qarun Lake; it rises on a kom with a 
characteristic oval shape, with ruins and buildings in mud- 
bricks. Unfortunately the increasing popularity of desert tourism 
is seriously risking the good preservation of the site. 
From an archaeological point of view the site is not well known 
and little has been published about it; in the past there have been 
many excavations (Grenfell and Hunt in 1900-1901, Zucker in 
1909-1910, Ahmed Bey Kamal in 1916), but the only scientific 
research of the area happened in 1932 by the Archaeological 
Mission of the Michigan University, directed by E.E. Peterson. 
  
Figure 1. A view of Soknopaiou Nesos (from North). 
The Italian Joint Archaeological Mission of the Universities of 
Bologna and Lecce, directed by S. Pernigotti and M. Capasso, 
started working at the town in 2001, to begin a project of 
documentation and study of the archaeological remains (Davoli, 
2004). The first map of the site was the one produced by K.R. 
Lepsius in 1843 and reproduced in figure 2 (from Davoli, 
1998); in the city are clearly visible the large temenos, enclosing 
498 
the Temple area, in the North and the long dromos in the North- 
South direction. 
During the topographic campaign carried out in February 2002, 
a wide-range of different geomatic techniques were applied: 
GPS, total station survey, photographic visual reality, aerial and 
close-range photogrammetry. Moreover, VHR (Very High 
Resolution) satellite imagery of the area was subsequently 
acquired. All the metrical and non metrical information is 
recorded in a common reference system for the creation of a 
GIS for the archaeological site and the surrounding area. A 
similar approach was followed for the site of Bakchias in the 
same region of Fayyum (Bitelli et al., 2003b). 
The paper describes in particular the acquisition and digital 
processing of low-height aerial imagery to produce very large- 
scale mapping of the area. 
A large number of non metrical images were acquired from an 
ad-hoc realized autonomous system based on balloon, to face 
the difficulties in realizing a traditional aerial photogrammetric 
survey in this region. The data were used to produce an 
orthophotomosaic of the site, the first digital metric map of this 
kind for Soknopaiou Nesos; it provides a high-quality detailed 
photographic and metric description of the numerous, often 
semi-buried, structures and their relationships. 
The work and the obtained results are presented, pointing out 
the problems concerning the collection of DTM, caused by the 
non conventional geometry of the photogrammetric block and 
by the presence of high-rise walls; besides the DSMs derived 
from various image-matching strategies were compared with the 
DTMs obtained by the GPS kinematic survey. 
Intern 
    
   
  
  
   
   
   
  
    
   
  
  
  
  
   
   
    
  
   
   
     
   
    
   
    
   
   
   
   
   
   
   
    
   
    
     
  
  
  
  
    
    
   
   
    
  
   
    
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