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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
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Orientât 
ion 
characte 
ristics 
Length 
characteristi 
cs of the 
road 
Area 
characteristic 
s of dry land 
Figure 7 spatial relationship between the characteristics of space 
3 Map symbol system model 
3.1 The symbol administrative system 
Based on object-oriented geographical entity management 
thinking, the entity is the combination body including attribute , 
geometry object , symbol object. The symbol is the entity 
outside manifestation , is to take entity as basis , is that the 
symbol is with the support of geographical feature entity, the 
geometry object with the entity is consult generate a map 
symbol. 
Figure 8 symbol administrative system 
3.2 The symbol organization system Recommend by the 
same token 
The map symbol is a independent element of entity , has whose 
oneself organization system and rule. Come to organize a map 
symbol for the model adapting to above-mentioned entity data 
organization, in the map symbol recommend the object-oriented 
thought by the same token, by inheritance, derived from the 
level of organizational structure to map symbols. The root 
taking entity as data organization , the basis being the symbol 
data organization. The symbol comes to manage according to 
the basic symbol, the element, a entity symbol correspondence 
is a basic symbol , a basic symbol can organize from many 
about element symbol ,the symbol-maker of point, line , region 
can organize the basic symbol being in the state of the geometry 
object of the entity , generate a symbol from map cell on 
symbol-maker basis, as shown in Figure 9. 
Figure 9 The symbol organization system Recommend by the 
same token 
The basic symbol is the symbol of the basic organizational unit, 
it provides the type of symbol, the only code , attributes and 
symbols of that information remarks etc.; 
The unit symbol is the symbol base unit, it is in charge of 
symbol organization concretely , including that fundamental 
symbol geometry type , additional geometry information , 
geometry consult location etc; 
The symbol generator is the organizer who is responsible for 
organizing basic element, it has stipulated the organization law 
and way of the unit symbol; 
Auxiliary element is need to define in generating process in 
symbol, for instance location , numerical value , attribute , 
characters etc. 
Basic element is to be composed of symbol , it is the parameter 
for stipulating the element’s various type . 
3.3 Basic element system 
Be based on the national standard regulation to the map symbol, 
for adapting to the changeful map symbol, setting to basic 
element mainly includes the following type : 
• Line segment: From starting point, coordinate and 
destination coordinate and the other fundamental 
graphic parameter generates straight line segment, 
Illustration 10 (a). 
• Rectangle: From the rectangle, central point 
coordinate and long width and the other fundamental 
graphic parameter generates a rectangle , Illustration 
10(b). 
• Triangle: Long from triangle base central point 
coordinate and base height and the other fundamental 
graphic parameter generates a triangle , Illustration 10 
(c). 
• Point: From central point coordinate and the other 
fundamental graphic parameter generates 
point; Illustration 10 (d) 
• Circle: From central point coordinate and radius of 
the circle and the other fundamental graphic 
parameter generates a circle; Illustration 10 (e) 
• Arc: From the central point coordinate, radius, 
start-stop angle of the arc and the other fundamental