INTEGRATION OF DIGITAL PHOTOGRAMMETRY AND LASER SCANNING FOR 
HERITAGE DOCUMENTATION 
Yahya Alshawabkeh', Norbert Haala 
Institute for Photogrammetry (ifp), University of Stuttgart, Germany 
Geschwister-Scholl-Strasse 24D, D-70174 Stuttgart 
yahyashaw@ifp.uni-stuttgart.de 
Commission V WG 4 
KEY WORDS: Cultural Heritage, Photogrammetry, Laser Scanner, Fusion, Linear surface features, Semi-automation 
ABSTRACT: 
Within the paper the potential of combining terrestrial laser scanning and close range photogrammetry for the documentation of 
heritage sites is discussed. Besides improving the geometry of the model, the integration aims on supporting the visual quality of the 
linear features like edges and cracks in the historical scenes. Although the laser scanner gives very rich surface details, it does not 
provide sufficient data to construct outlines for all surface features of the scanned object, evene though they are clearly defined in the 
reality. In our approach, information on edges and linear surface features is based on the analysis of the images. For this purpose an 
integrated segmentation process based on image data will support the extraction of object geometry information from the laser data. 
The approach applies image based semi-automated techniques in order to bridge gaps in the laser scanner data and add new details, 
which are required to build more realistic perception of the scene volume. The investigations and implementation of the experiments 
are based on data from Al-Khasneh, a well-known monument in Petra, Jordan. 
1. INTRODUCTION 
The generation of 3D models of historical buildings is 
frequently required during the documentation of heritage sites 
i.e. for tourism purposes or to provide education resources for 
students and researchers. During the generation of these models, 
requirements such as high geometric accuracy, availability of all 
details, efficiency in the model size and photo realism have to 
be met by the different approaches used for data collection [EL- 
Hakim et al 2002]. One well-accepted technique frequently 
applied in the context of heritage site documentation is close 
range photogrammetry [Gruen et al 2002, and Debevec 1996]. 
In the past decade, these traditional terrestrial approaches have 
also benefited from the fact that digital image collection is now 
feasible with of-the-shelf cameras. Thus the efficiency of 
photogrammetric data collection could be improved 
considerably by the integration of semi-automatic tools based 
on digital image processing. Additionally, laser scanning has 
become a standard tool for 3D data collection for the generation 
of high quality 3D models of cultural heritage sites and 
historical buildings [Boehler and Marbs 2002]. These systems 
allow for the fast and reliable generation of millions of 3D 
points based on the run-time of reflected light pulses. This 
results in a very effective and dense measurement of surface 
geometry. Current limitations regarding the measurement rates, 
accuracy, or spatial point density will further disappear in the 
near future, thus laser scanning seems to become the 
dominating approach for the generation of 3D documentations 
and presentations of heritage sites. 
Despite the considerable progress of these approaches, there are 
still some limitations, which have an effect on the quality of the 
final 3D model. Even though current laser scanners can produce 
large point clouds fast and reliably, the resolution of this data 
  
" Corresponding author 
can still be insufficient, especially if edges and linear surface 
features have to be collected. In the contrary, the digital 
photogrammetry is more accurate in outline rendition, 
especially if they are clearly defined in the reality. On the other 
hand, image based modeling alone is difficult or even 
impractical for parts of surfaces, which contain irregular and 
unmarked geometrics details. Additionally, the identification of 
points to be measured, being manual or semi automatic, requires 
a long and tedious work, especially if a considerable number of 
points has to be captured. 
The complete coverage of spatially complex objects like 
heritage sites can only be guaranteed, if data collection is 
realized from different viewpoints. Even though this is possible 
in most scenarios, problems can result from the fact that setting 
up and dismounting the complete laser system is relatively time 
consuming. In contrast to that, the effort to collect additional 
images with a standard digital camera can almost be neglected. 
Additionally, compared to laser scanning there are fewer 
restrictions on the range of measurements during image 
collection, which simplifies the selection of different viewpoint 
in order to cover the complete structure of the object. For this 
reason, it can be advantageous to complete a geometric model, 
which has been generated from the laser measurement, based on 
intensity images captured independently from the range data. By 
these means object geometry, which is not available in the range 
data due to occlusions is provided based on photogrammetric 
measurements. 
Thus, the highest possible degree in efficiency and flexibility of 
data collection will be possible, if both techniques are combined 
during data processing. In our approach this integration helps to 
improve the geometry and visual quality of the collected 3D 
model. During data collection the information on edges and 
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