measured by it’s size and computed from the number it 
correspond to. 
We propose the CONTRACT to describe when a object 
decreasing it’s space that occupied in the geo-spatial way, as a 
result of CONTRACT process, geometrical area or volume 
reduced in a computable way, CONTRACT is a original 
process. 
Rotation plays an important role in the geometric 
transformation, change the direction of the object by adding or 
decreasing the angle from the axis, a lot of geographical 
phenomena related the changing of orientation can be displayed 
by ROTATE. 
We propose MOVE a basic process for the independent change, 
the object change it’s position from one place(often marked in 
certain coordination) to a different place, MOVE process 
provides a broad range of phenomena such as changing address. 
Regardless of the identity and the related change happened to 
other objects, EXPAND, CONTRACT, ROTATE and MOVE 
comprise of the independent change, which created a basis for 
basic spatio-temporal process. We deem independent change as 
a original level of spatio-temporal process, and dependent 
change a higher one, in many cases, independent process 
happened as a result through the dependent process. The 
classification of STP do benefit for the following section, and 
built a fundamental basis for the visualization of STP, in the 
following paragraph, numerous variables will be utilized for the 
displaying of the STP, with respect to each process under the 
framework proposed here. 
3. DYNAMIC VARIABLES AND TEMPORAL 
MAPPING 
It has become clear that the traditional visual variables, which 
we will call the static visual variables from here on, do not 
suffice in describing the added means of expression we have in 
dynamic visualization of spatio-temporal processed through 
cartographic animations. To this end six "new" visual variables 
including moment, duration, frequency, order, rate of change, 
synchronization have been introduced by DiBiase et al. (1992 ) 
and MacEachren (1994) . These will be called the dynamic 
visual variables from here on. 
Research by DiBiase et al. (1992) and Koussoulakou & Kraak 
(1992) has shown that visual variables can indeed be used on 
the individual frames of an animation in such a way that these 
images effectively communicate the cartographic message to 
the user, while the movement of the animation gives the 
message an extra dimension and "new energy". Furthermore, 
the findings of Koussoulakou & Kraak (1992) showed that 
using animated maps helped users grasp the contents of a 
message in a more effective manner compared to using 
traditional static maps or map series. 
3.1 Four Implementai Dynamic Variables 
In this paragraph, in order to get an implementai framework of 
dynamic visualization for the STP, we chose Moment, Duration, 
Order and Frequency for the representation of temporal aspect 
of objects, there are the reasons for the choice: 
3.1.1 Moment 
In most time, we look process time as a continuous variable, 
however, each process can be divided into discrete time pieces, 
we call it MOMENT, The moment that an element in the map 
changes during a STP can be used for temporal as well as non 
temporal animations, e.g. every procedure has a begin time and 
end time, some key remarkable MOMENT are often record in 
spatio-temporal database. 
3.1.2 Duration 
From the Start to the end, the time span that between two 
different MOMENT is named DURATION, we can also name 
it after from one specific state to another state of objects or 
phenomena, The last time always is an important item in the 
geographic information, e.g. how long will be typhoon last. 
3.1.3 Order 
Order is used to differentiate change sequence among several 
spatio-temporal changes, sometimes we use a frame according 
to a specified spatio-temporal process, The order of change is 
similar to the topological relationship or spatial neighborhood, 
in one hand ,the sequence of the frame can be represented by 
ORDER, in the other hand, order also refers to the order of 
phases in a series of changes in the spatial domain. 
3.1.4 Frequency 
Frequency refers to the number of times that a phase is repeated 
in a series of changes in the spatial domain. It is also used to 
determine how the frame for representing the STP to be 
repeated, since a lot of phenomena reoccurs according to a 
regular time, here the frequency can conceptualize this 
phenomena very well. 
Altogether, the variable mentioned above may not sufficient to 
describe all the STP representing the objects and phenomena, 
however it can build a implementai framework for a practical 
implementation. 
3.2 Temporal Mapping 
There are at least three kind of time for the spatio-temporal 
object, Real World Time, Database Time and Display Time, 
when dealing with a temporal process a direct relation between 
display time and world time exists. World Time is the time 
scale of reality, the moment an event takes place in the real 
world. Examples of these processes are those of the Dutch 
coastline from Roman times until today, boundary changes in 
Africa since the Second World War, or the changes of 
yesterday's weather. Time units can be seconds, weeks, or years. 
In order to represent the spatio-temporal process in a dynamic 
(animated) way, the mapping from Real World Time to Display 
Time is necessary, because it is impossible to display a time 
sequence change according to actual time. Figure2 show a 
relation between Real World Time to Display Time, T1 and T2 
are world time, Display time Tl’ and T2’ are derived through a 
mapping. All this time are recorded in the Database time, that 
means that Database Time is a complete record temporal 
variable aggregation. Not only the transactional time but also 
the Real World Time and Display Time are derived from it.