Dowman, Ian 
  
TOWARDS AUTOMATIC RECONSTRUCTION OF VISUALLY REALISTIC MODELS OF 
BUILDINGS 
Masood Varshosaz, Ian Dowman, Dave Chapman 
Department of Geomatic Engineering, University College London 
Gower Street, London, WCIE 6BT, United Kingdom 
varshosaz@hotmail.com, idowman@ ge.ucl.ac.uk, dchapman@ ge.ucl.ac.uk 
KEY WORDS: Visually Realistic Models, 3D GIS, Texture mapping, Automatic, Buildings, Modelling. 
ABSTRACT 
This paper describes an innovation in the field of texture creation for the construction of Visually Realistic Models (VRMs) 
of buildings in urban areas. The development of an Automatic Texture Processing Tool (ATPT) is described which uses 
registered CCD images, captured in a special manner, and a Numerical Frame of Reference (NFR) to create textures of 
individual faces of buildings. The images are acquired on a virtual sphere using a CCD camera which is mounted on a 
servo-driven theodolite and are indexed using the angular readings from the theodolite. The registration of the images 
includes the calibration of the data capture unit and the localisation of the imaging stations. In order to process the 
textures, the coordinates of building faces, extracted from the NFR, are passed to the ATPT. The ATPT finds the corre- 
sponding images covering each face and forms the textures by extracting, rectifying, and mosaicing the image portions 
automatically. 
The system not only enables the automatic creation of textures, but also allows one to make highly accurate measurements 
on the resulting VRM, a task which is not possible using conventional texture processing systems. Textures of a specific 
face can easily be merged in order to obtain an occlusion-free or higher quality texture. Moreover, independently formed 
NFRs can be used to initialise the texture creation process. 
1 INTRODUCTION 
À Visually Realistic Model (VRM) is a digital 3D representation (eg Figure 1) which contains all the information neces- 
sary to view and recognise an object from all directions. It not only shows the geometric relationships but also permits 
realistic renderings of objects. Such three dimensional realistic representation provides designers, planners, the public, 
and the others with imagery closely coupled with the human experience and, hence, is of great interest (eg Varshosaz, 
1997; Brenner and Haala, 1998; El-Hakim et al., 1998). 
  
Fig. 1: Visually Realistic Model of University College London. 
The need for VRMs of cities is evident from numerous applications such as city planning, architecture, entertainment, 
education and training, tourism, and disaster preparedness. In the recent years, there have been a number of advances in 
the techniques developed for the production of VRMs of buildings. The major improvements have been in the use of laser 
scanners and the direct use of photographs for modelling and rendering of scenes. 
  
180 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B5. Amsterdam 2000. 
  
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