= Vi J 
WM P o VU Wd 
re 
ww 
pra} bu ii 
Le Az 
N N 
LDi Ci 
Du reda (4) 
4.2.2 The Variety of Viewfield: M3' For 
  
a definite viewfield given, its variety can be 
obtained through calculating the variety of visual 
lines and visual surface. M3, the variety of 
visual lines, can be calculated as follows: 
Fig.4 shows a landscape visual model. On DTM, 
derive. all. height points .Xi, Yi, Zi from the 
landscape visual model as shown in Fig.5 and 
Fig.6 (1-1,2,3,....-. ,N-). 
Centre of the ball 
View distance R 
  
Fig.4 A landscape visual model (ball-like space 
H(Z) € Ss 
E3000, co r500 R250m XP,YP,ZP\ | Xi,Yi,Zi 
IS RE x 
  
  
Fig.5 A landscape visual model (ball-like space 
of viewplace, point Po stands for viewer 
position) 
Ni Points Xi,Yi1,7i N > 
/ X 
Po [8 
   
3 1] Il s. 
»yi,.2i 
PLAN SECTION I-I PLAN SECTION II-II 
Fig.7 Graphics 
of B and a 
Fig.6 Calculation of 
the x,y,z coordinates 
of every point 
22 - à 
8 2 1 
D (5) 
^ (X2-X1)?* (Y 2X1)? 
Y= sin 5 Slop = sin 
283 
Then, calculate y of all the points within the 
ball, T: (1z1,25....-... ,N,), and make statistic 
analysis of it: 
  
N 
ou (6) 
(7) 
The variety of viewfield: 
M3'-k, M3«k4Ml. (8) 
The k, and k, are coefficients of the weight. 
4.2.3 The Landscape Kuang-Ao Elements 
As examples, the calculations of four Kuang- 
a elements will be introduced as follows: 
1) Spatial Limit of Viewplace :Rh 
37: 
1 
Rh = Zp fre Ni-1 (9) 
Zp is the height of viewer's position; Z; is the 
height of any point within the ball (Fig.8). 
fn 
S I-I 
Fig.8 Graphic of the calculation of Rh 
  
2) Viewplace Slope:SLM 
  
  
  
  
  
  
  
  
  
25-2 
SLM = = N (10) 
Z2 
Z1 
Hd Z1 11-11 
Fig.9 Graphic of the calculation of SLM 
3) Viewplace Aspect : SLA 
stu 11 
SLA = tg x (11)