ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001 
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3.2 THE IMPLEMENTATION OF THE COMPOSITE 
TEMPORAL DATA MODEL 
The implement of the composite temporal data model (tab.2) is 
described. 1. Open initial cadastral database, exhibit the current 
cadastral state as initial cadastral state in that it is accessed 
more frequently than any other historical states in general. 2. 
Open time-privilege database. 3.Input given time, users’ login 
IDs and their passwords. 4. if OK, retrieve the backup file—the 
closest to given time, as initial cadastral file; otherwise, Close 
and Return to the current state; 5. Open action database and 
restore changed land-parcels according to action records until 
the current state fully accords with the state at given time. Thus, 
historical state of given time is restored completely. Moreover, 
table.2 the retrieval of historical states flow chart 
the time of restoring historical state is quite short. The reasons 
are IThe cadastral map and the base map are stored into 
separate layers. While only cadastral data, which are quite fewer 
than other data, are processed in historical data management,; 2. 
What’s more, only changed cadastral data —‘delta variables’, 
which record the differences between the previous states and 
the current state, are recorded into the actions database; 3. 
Because snapshots about cadastral maps of different time points 
are stored in initial cadastral files, the backup cadastral snapshot 
- the closest to given time point can be quickly retrieved as 
initial cadastral state, on the basis of the initial cadastral state, 
the changed spatial units—land-parcels are quickly restored 
according to action records in action database.