static geographical data, the dynamic symbol base built up a 
framework for two kinds of dynamic symbol as follows: 
4.2.1 Temporal Symbol 
Lots of spatio-temporal processes are successive procedures 
that can be displayed in a continuous representation, in the 
paper, we adopt temporal symbol to visualize such kind of 
successive processes. By the combination of dynamic variables 
and traditional variables such as colour, size, opacity and so on, 
the process can be displayed well. For example, urbanization 
can be showed vividly by temporal gradually size-changed 
polygon, etc. 
An example of the temporal symbol is the addition of 
subsequent map layers, which leads the viewer through a theme, 
to help understand spatial and contextual coherence. This leaves 
this types of cartographic animations, which are the core of the 
classification presented here. It is the relation between spatial 
data's components and display time which distinguishes them 
from each other. 
4.2.2 Non-temporal Symbol 
A number of phenomenon are not so strictly related to the 
whole process of apatio-temporal objects, however, some 
character at specific moment need to be highlighted. Non 
temporal symbol is not strictly linked with world time, the 
display time of it is applied to explain spatial relations by 
presenting individual images in logical sequence. Some 
techniques will be used to demonstrate highlights or emphasis 
of spatio-temporal processes, such as the blinking and flashing 
of point symbol. Another example of this is to show a data set 
in different graphic representations, such as an isoline map, an 
smooth statistical surface or a dot map to provide the viewer a 
comprehensive impression of the same data set. 
4.3 Visual Interface for Dynamic Control 
For the user of a dynamic symbol, it is important to have tools 
available that allow for interaction while viewing the animation. 
Seeing the animation play will often leave users with many 
questions of what they have seen. Just a re-play is not sufficient 
to answers questions like 'What was the position of the coastline 
in the north during the 15th century?' Most general software to 
view animations already offer facilities such as 'pause', to look 
at a particular frame, and '(fast-) forward' and '(fast-) backward', 
to go to a particular frame. More options have to be added, such 
as a possibility to directly go to a certain frame based on for 
instance a temporal query, or the ability to re-ordering 
individual frames based on a attribute query. This becomes 
especially relevant if we realize that animation will not only be 
used to present spatial data, but will be increasingly used in an 
exploratory environment. In such an environment the animation 
is just one of the alternative view one has available to study the 
data at hand (Dykes et al., 2005). 
We designed a visual interface that help users to manipulate the 
process of displaying, through which people can play back and 
query some details of the Spatio-temporal process. A speed 
control function of the process also provided for different 
velocity analysis. User can get a vivid impression of the change 
that had happened from the data which are stored in the spatio- 
temporal database. 
4.4 Test and Analysis 
A test of the implementation of the framework is carried out 
based on the residential expansion of a city of BAOJI in the 
northwest of shananxi province in China. The following graph 
diagram shows Entity-based spatial-temporal process displaying 
based on dynamic symbol base. An urban growing process can 
be showed by a series change through dynamic symbol. 
T1 T2 
Figure 4 Time series change showed by temporal symbol 
5. CONCLUSION 
Dynamic Symbol offers the user the opportunity to see and 
query changes spatial patterns. Depending on the nature of the 
data one can apply different design techniques, or change the 
viewpoint on the data. Dynamic Symbol will offer a better 
insight to mapped phenomena. However, this will only work 
when the user environment has the proper options for 
interaction. In an exploratory environment the dynamic symbol 
will be one of the strong alterative views on the data that 
supports knowledge discovery. 
REFERENCES 
Koussoulakou, A. & M.J. Kraak (1992). Spatio-temporal maps 
and cartographic communication. The Cartographic Journal, 29 
(1992) 2, pp. 101-108. 
Kobben, B., Yaman, M.: Evaluating Dynamic Visual Variables. 
In: Ormeling, F.J.,Kobben, B., Perez Gomez, R. (eds.): 
Proceedings of the Seminar on Teaching Animated 
Cartography. International Cartographic Association, Utrecht 
(1996)45-51. 
Mennojan Kraak, Arjen Klomp. A Classification of 
Cartographic Animations: Towards a Tool for the Design of 
Dynamic Maps in a GIS Environment [C]. The Seminar on 
Teaching Animated Cartography, Spain, 1995, 
http: //cartography. geog. uu. nl/ica/Madrid/kraak. html. 
Masuoka P, Acevedo W. , Fifer S. , Foresman T. 1996 .Tuttle 
M. Techniques for visualizing urban growth using a temporal 
GIS database .Presentation at the ASPRS/ACSMAnnual 
Convention andExhibtion, Baltimore, MD, pp.22- 25. 
ZHU Guorui, 2004. Cartography. Wuhan University Press, 
pp.34- 35. 
AI Tinghua,1998. Dynamic symbol and dynamic map. Journal 
of Wuhan Technical kUniversity of Surveying and Mapping. 
23(1),pp.47-51