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4. About OOP database system 
A mature OOP language used for GIS application has 
not yet been available in the market. Therefore, the 
database of the existing GIS software such as 
ARC/INO...,etc. can still be used as the data source and 
graphic output device. 
The traditional GIS database systems are record 
oriented, which is to say that the date they contain are 
filed record by record, rather like cards in a conventional 
card file. Consequently, they are not suited to 
representing a conceptual data model of geographic 
reality well. In a famous relational database, all the 
elements that together comprise a particular map object 
may put in several records in various tables. However, 
geometrical data and attribute data are often physically 
separated. They are in a separate database. 
To represent the real world more faithfully, Object- 
oriented database systems organize the data of the world 
according to the objects, which are homogeneous, and 
with various internal and external relations among them. 
in object-oriented systems, it becomes possible to 
practice data in a similar way to store data. Objects are 
manipulated as independent homogeneous entities. 
Those entities may comprise several other objects in a 
hierarchy. 
   
  
  
Data Model Data Model 
Relational Object-oriented 
Database 
  
Fig. 1 Object-oriented database (b) compared to a 
relational database (a). (Adapted from Tor Bernhardsen) 
5. Some specific explanations and 
analyses about the object-oriented and 
user-oriented data model 
9.1 The variety requirements of the users 
Theoretically, diversifying of the users’ requirements may 
appear in the applications of the GIS in the following 
aspects: 
» In the global, continental, regional (such as: Asian 
and Pacific region,...,etc.), national, provincial or 
state, county, urban, town, rural aspects,...,etc; 
* In the various trades, such as: industry, agriculture, 
commerce, military ... etc; 
* in the various governmental departments, such as: 
planning, finance and taxation, ^ industry 
departments,... etc.; 
On or under the various lands, coastal areas, Island, 
and in the sea... ‚etc. 
375 
For the GIS data modelling all these users' requirements 
. Shouid be considered. The problem is how to satisfy such 
a huge requirement. 
Diversifying of the users' requirements and huge amount 
of the data make the GIS more and more complex and 
expensive. This is not only for the acquisition of the data, 
but also for the processing and updating of the data. 
However, in developing countries, it is very difficult to 
afford such a huge project not only for the funds, but also 
for the education and the new technologies involved. The 
GIS is rather a new technology. it integrates the 
computer science, surveying and mapping, remote 
sensing, geography, cartography, information science 
and,...,etc. The people involved in this field are usually 
not familiar with this new technology. 
In order to simplify this new technology, we suggest: 
For the different users the GIS can be started in a 
relatively small project according to their most 
practicable and possible requirements, and extended 
later according to their needs and possibilities gradually. 
Therefore, the data model could be designed in three 
classes: Basic objects class, users specific feature object 
class and newly increased and supplementary class. 
5.2 Data classification of the GIS data model 
According to the consideration above, we suggest that 
our data model will not be covered with everything, but 
the initial data model ought to predict some users’ needs 
and their conditions, and it will be extended later 
according to their needs and possibilities gradually. In 
order to make the project simple and clear we will 
consider that the users can be all over the world, but ail 
the users will be restricted for tourism in Hainan province 
only. 
5.2.1 Basic class of the data model 
The objects of the basic class will be common for all the 
users (tourists) who are intended to participate in the 
tourism in the Hainan province. The contents of this 
class will have: 
e Building: 
Schools 
    
   
   
Building 
  
Commercial 
Nir” 
Fis 
Fig.3 Building for the basic class of the data model 
Building in the commercial and residential district; 
building of some financial institution, transportation unit, 
entertainment unit, sports unit, and tourist service unit; 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996