e Each floors are connected with stairs, where 
present, so that a path could be found between a 
line given pair of points with a search for a minimum 
path. 
Figure 19 is a perspective view of the Nishi- 
shinjuku area with the translucent terrain surface, 
| and Figure 20 shows a cross sectional view. 
    
   
    
    
LS 
= Subw, ¥Y Star 
'Maruno,,.. 
1gs 
    
   
   
   
  
   
Station (Keio line 
mu 
tal 
ue. 
he 
Figure 19 a) A perspective view from 
ablove the east side of Shinjuku station 
are 
the 
ces 
ld, 
ion | 
ain 
the 
5 of 
me 
> to 
of 
the 
ong 
s to 
and 
aint 
Figure 19 b) À pespective view from under the ground 
has 
‘the 
the 
e of Figure 17 An example of a 2.5D surface 
(terrain surface) 
  
the 
ngs. 
‚ven 
zure 
jon. 
ons 
two 
not 
man 
iges 
ting 
Figure 20 À cross sectional view of buildings and 
underground structures 
7 CONCLUSIONS 
The conclusions of this study are summarized 
as follows. 
1) Basic requirements for a Digital Urban Space 
Model(DUSM) are reviewed. The discussion 
concludes that among the existing solid 
modelling methods, the BR model is promising 
but that the input and update of 3D spatial data 
with the BR model are prohibitively labor- 
demanding. 
2) A model (Surface Representation(SR) model) 
for 3D urban spatial modelling is proposed 
which introduces a "surface" into the 
conventional BR model. With a SR model 
based on 2.5D surfaces, the efficiency in 
SD 
, the 
ond 
Sting 
h as : ; : 
d be Figure 18 A result of terrain surface interpolation 
ome 
DOTS. 
  
263