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NIV 
  
OBJECT MODELLING AND VISUALIZATION IN ARCHITECTURE 
M. Stephani and L. Tang 
Chair for Photogrammetry and Remote Sensing 
Technical University Munich 
Arcisstr. 21, D-8000 Munich 2, Germany 
Tel: + 49-89-2105 2671; Fax: + 49-89-280 95 73; Telex: 522854 tumue d 
E-mail: tang@photo.verm.tu-muenchen.de 
Commission V 
ABSTRACT: 
A complete documentation of an architectural object 
covers both the geometric aspect and the pictorial 
one. While the pictorial information of the object is 
often delivered in the form of conventional photo- 
graphs, the geometric modelling can usually be per- 
formed by photogrammetry. Using surface modelling 
techniques and digital photogrammetric tools (e.g. 
digital orthoprojection) the geometric and the pictor- 
ial modelling can be integrated in a complete system. 
Triangulated irregular networks are most suitable to 
describe object surfaces. With the help of raster com- 
puter graphics, surface models can be visualized in 
different ways. Experiences with modelling and vis- 
ualization of architectural objects are presented. 
Examples demonstrate the applicability of the pro- 
posed procedures. 
Keywords: surface modelling, visualization, triangu- 
lated irregular network, architectural object, architec- 
tural photogrammetry, architecture information 
System. 
1. INTRODUCTION 
To document an architectural object, line maps ob- 
tained by e.g. photogrammetric stereo plotting are 
usually used. Since they constitute a part of the ge- 
ometric aspect of the object only, certain information 
concerning e.g. the appearance of the object should 
be added. Therefore, conventional photographs are 
simply the carrier of issues like paintings, mosaics, 
tiles, marble incrustations and other decoration ele- 
ments. In many cases, however, line maps seem not to 
be sufficient for representing the whole geometric 
issue of an architectural object. On the other hand, 
documenting an object digitally is promised by com- 
puter technologies nowdays and delievers a broader 
flexibility than the analogue documentation men- 
tioned above. For instance, an architectural object can 
geometrically represented by one or more digital sur- 
face models (DSMs) instead of line maps. DSMs can 
then be visualized by means of raster computer 
graphics pictorially. For a better understanding of the 
object, digital ortho images can be generated 
(Mayr/Stephani, 1988) and displayed in different ways 
(Stephani/Tang, 1990), both based on available DSMs. 
This paper presents some experiences with modelling 
and visualization of architectural objects. A system is 
proposed for achieving a complete documentation of 
architectural objects using modern computing tech- 
niques. Practical examples are given. 
2. AN INTEGRATED SYSTEM 
As illustrated in Figure 1, a complete documentation 
of an architectural object can be achieved in an inte- 
grated system, consisting of photogrammetric recor- 
ding, data acquisition, data preparation, object 
modelling, visualization, data management and ana- 
lysis. 
Photogrammetric Recording 
Data Acquisition 
Data Preparation 
   
   
    
  
  
  
  
  
  
  
  
  
Fig. 1: An integrated system for architecture do- 
cumentations.