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The 3rd ISPRS Workshop on Dynamic and Multi-Dimensional GIS & the 10th Annual Conference of CPGIS on Geoinformatics
Chen, Jun

ISPRS, Vol.34, Part 2W2, “Dynamic and Multi-Dimensional GIS", Bangkok, May 23-25, 2001
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The city terrain is needed to show 3D city scene. Comparing to
building model, the required of city terrain model is simple. In
order to improve the efficiency in 3D visualization city on
Internet, we select the GRID model that is a kind of DEM model
to construct the city terrain.
To visualization the GRID model, we divide the quadrangle into
two triangles. Figure 2 shows the city terrain with the GRID
Fig. 2: GRID Model
The system architecture has been designed to implement
visualization the 3D city data on Internet. For visualization the
Web 3D data, some researchers (Lindenbeck, 1998,Siyka
Zlatanova, 1999) have presented the client-server architecture.
The client-server architecture is proved to be stable for Internet
communication. Compare to the approach presented in (Coors,
1998), our approach uses 3D GIS Applet to visualize and
interact with data. The approach can also manipulate and
query respectively on the server and client station. In order to
efficiently manage large 3D building data in database at
server-side and query the building attribute data from the
client-side, the R-tree structure is proved to be a useful index
(Gruber, 1998). According to the LC model and R-tree index in
database, the way to query the attribute data of building is
3.1 The system architecture
The system architecture for visualization and query on Internet,
presented here, is typical client-server architecture. (See
Figure 3) In this architecture, the city buildings attribute data
are stored on the server(s) database. The process of
client-server communication can be described shortly as
follows: The client-side downloads a 3D GIS Applet from the
server-side by Web browser. This Applet runs on client-side to
show the 3D scene and communicate with the server. Some
behaviors have been implemented at client-side. Using these
behaviors, the user can walk through the 3D scene by mouse
or navigate the 3D scene by keyboard. Especially, they can
designate the flying route from a 2D map to fly over the 3D
scene. The building at the 3D scene can be picked and get the
building- ID which identifies the building. The 3D GIS Applet
sends the building-ID to the Web server and the server can
return the building attribute data to the client-side. With this
process, the building attribute can be queried at client-side.