on 
lationships 
ases) were 
ie corridor: 
ling, were 
ed to this 
coordinate 
ich system, 
f a simple 
coordinate 
4 & 5) and 
; (figures 6 
  
  
ion in order 
office. The 
ases of the 
with their 
ate the pa- 
inks the va- 
te system. 
ordinate 
d in bold) 
  
Figure 8. 3D surface and photorealistic models of the corridor 
and the classrooms or offices 
32. Example of an outdoor scene 
Although the method of 3D modeling proposed in this study is 
intended for indoor scenes modeling, it can also be applied to 
exterior scenes if their geometry is described by means of plane 
surfaces. To show this possibility, this method was used to 
establish the 3D model the old city hall of Zurich (Switzerland) 
from images proposed by CIPA in a dataset (Streilein, 1999). 
32.1. Steps of 3D single image modeling of the old 
Zurich city hall 
Used images 
Two images, taken from the dataset, were used to carry out the 
geometric model of the building. The first one covers the north 
and east facades whereas the second covers north and west 
facades. With regards to the south facade, it can be modeled by 
means of points measured on the east and west ones. 
Both selected images satisfy a perspective projection. This 
allows the calculation of vanishing points associated to the 
various axes of the local coordinate system. 
Local coordinate system 
To configure the scene for a single image modeling, a local 
coordinate system was set up and control points were defined 
(figure 9). This system must not be a right hand system. Four 
control points were chosen on the north fagade, considered as 
the reference plane of the scene. 
  
Figure 9. Local coordinate system and control points 
The same coordinate system was used to extract 3D coordinates 
of points measured on both images indicated in figure 9. 
Modeling with our application of single image modeling 
To extract the 3D geometry of the Zurich city hall of by using 
our application of single image modeling, the following stages 
were applied: 
l. Definition of two single image projects. Each project 
requires an image, a file of control points and a camera file 
(optional); 
2. Computation of the vanishing points associated to the local 
coordinate system axes. This is done by measuring a series of 
parallel lines for each axis in the image; 
3. Calibration of the camera by means of vanishing points 
resulted from the previous stage; 
4. Computation of the homography of the north fagade. This 
is done with the four control points given in the dataset (figure 
9); 
5. Computation of the scale factor associated to the reference 
direction(Z) by using a reference distance measured along this 
direction; 
6. Determination of the 3D coordinates of the points 
measured on the various façades; 
7. Establishment of a relational database by means of the 
interface integrated into the application of single image 
modeling. This database contains the semantic and topological 
data of the building; 
8. By means of the interface intended for topology-based 
modeling and integrated into the main shape of a CAD system, 
the visualization of building 3D surface model was done 
automatically. In this database the WALL as a semantic type 
represents the various facades whereas the semantic type 
CEILING represents the faces of the roof; 
  
Figure 10. 3D surface and photorealistic models 
of the city hall of Zurich 
By means of the CAD system, textures were attached to the 
various faces and' the 3D-photorealistic model was generated 
(figure 10). The textures of the various faces were calculated by 
means of 3D points measured on these faces. 
4. CONCLUSION 
An approach has been proposed to realize interior and exterior 
3d modeling of buildings from single images. 
This approach can be summarized in the following points: 
1. The approximation of the interior part as being composed 
of simple and reference unit components; 
2. The representation of the information in hierarchical form 
3. The simultaneous data structuring in a relational database. 
The RDBMS was chosen as the data processing tool. 
Considering the geometric characteristics of the buildings, a 
single image photogrammetry configuration was adopted as a 
source of the 3D geometric data. 
Three solutions were proposed to compute the 3D geometry 
from one image using our application for single image 
modeling, partly based on former researches. The 3D 
reconstruction and visualization of the imaged scene are based 
on the topologic relationships recorded in a relational database. 
To validate our method, the method has been applied on an 
indoor scene and an outdoor one. 
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