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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