ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001 
geographical entities resulting in status changing happen 
endlessly, capacity of data will increase infinitely. Constructing a 
data structure with reducing storage of unchanged data, 
representing time property of entity (especially temporal 
relationships) naturally and some efficient operators on the data 
structure are most important thing for us to consider while 
designing the composite temporal data model. In this model, 
temporal databases (tab. 1) are primarily composed of three 
components: initial cadastral files, action files, and time-privilege 
files. 
3.1.1 INITIAL CADASTRAL FILES 
Some snapshots about cadastral maps of different time points 
are stored in the in initial cadastral files. The less the storage of 
snapshots is, accordingly the less storage space will be 
occupied, the longer time of restoring historical states will be. On 
the contrary, the more the storage of snapshots is, the more 
storage space will be occupied and the shorter the time of 
restoring historical states will be. The number of storing 
snapshots is completely determined by the users’ requirement. 
3.1.2 ACTION FILES 
A series of actions (for instance, addition, deletion, splitting, 
mergence, e.g.) and related information (such as, time and 
indexes, e.g.) are stored in action files. In a real world, what time 
a spatial object changes is uncertain (For example, a parcel is 
combined with another parcel or part of another parcel today and 
perhaps the other parcel will be decollected tomorrow), so it is 
very difficult to mark a time point on the side of attribute field. In 
another word, the change of most spatial objects at one time is 
not continuous, which is interval, and the time period between 
two actions of change is not interpolated. This means that some 
information during the course may be lost and inaccurate picture 
of the real world may be stored. On the other hand, the smaller 
the time period between actions and time point, the more 
accurate the representation will be. However, capturing data at 
time intervals that are too small for requirement of the 
application would result in waste memory. In this model, choose 
to record temporal information only when entities change their 
states. In that case, the time intervals will be variable and 
determined by the frequency of actions. 
3.1.3 TIME-PRIVILEGE FILES 
Time and authorized information, such as users’ login IDs and 
their passwords, are stored in time-privilege files. The field of 
time is the link between action files and time-privilege files. In 
this model, all of spatial data and non-spatial data are stored in 
relational database. Authorized information of accessing the 
historical states can be set in time-privilege files as other 
attribute tables of the relational database. 
Action 
Files 
Time- 
Privilege 
files 
table. 1 historical data structure