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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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Jing CHEN [1] .Qingquan Ll [1] , Jianya GONG 111 , Bisheng YANG 111
|1) National Lab for Information Engineering in Surveying,
Mapping and Remote Sensing. Wuhan University
129 Luoyu Road, Wuhan 430079, P.R.CHINA
Email: ¡chen@wtusm.edu.cn ,lqq@wtusm.edu.cn ,bsvanq@263.net
KEY WORDS: 3D-city model, Visualization, R-tree
Following the development of the Internet technique and the growing interests in some applications, such as city landscape, real estate
management, call for three-dimensional GIS data to be handled via Internet. In this paper, we focus our researches on the three-
dimensional city visualization on Internet. Firstly, presenting the layer-combined (LC) model for city building model and the GRID model
for city terrain model. Secondly, the client-server architecture is designed to implement query and interaction. In order to speed up the
operations with the query analysis and fly over the three- dimensional city scene on the client-side, the R-tree organization of objects on
the server-side is presented. Finally, a system prototype (CWeb3D) for 3D-city model on Internet is developed which includes 3D
visualization and operation about querying 3D objects and some query analysis.
In recent years, the development in Internet GIS is very rapid.
Internet GIS provides users with access interactive, disturbing
geographical information. But most of Internet GIS software
only handles two- dimensional (2D) geographical data. It
cannot deal with the three- dimensional geographical
information better. Some researchers (Edmund SIDES
2000,Siyka Zlatanova 1998) have published three-dimensional
(3D) geographical data on the World Wide Web using Virtual
Reality Modeling Language (VRML) and Hypertext Markup
Language (HTML). However this method only views 3D
geographical data. It is not much better to query and operate
the 3D objects. Following the development of Internet
technique and some applications such as city landscape, real
estate management, The growing interest in 3D city data of
wide range of local and remote users demands a Internet 3D
GIS providing extended techniques for data query, visualization
and interaction with three-dimensional (3D) GIS data via
Internet, as well as, user-friendly, easy-to-use, standardized
Graphics User Interface (GUI).
In order to visualization and interaction with 3D city data via
Internet, building 3D city model is required. Up to now, so
many approaches about auto reconstruct and
semi-reconstruct building city model have been developed.
For example: CC-GIS (Wang. XH, Gruen, 1998), this system
includes vector and raster as well as attribute data and uses
point, line and surface describing a building. Forstner(1999)
construct building model from image using automatic and
semiautomatic acquisition method. Due to the complexity of
buildings, especially the roof of buildings, so many
researchers pay attention to the data model and structure. A
serial of data structures are taken into account, for instance:
CSG, BR, TIN, Grid, TEN, FDS and hybrid structure (Martin
J, 1992, Pilout M., 1994, R. Li, 1994, Molenaar M, 1992,
Qingquan Li, 1996). Although these methods are very
efficient in reconstructing buildings and visualization, most
of them are used at PC system or workstation system. They
are not used to construct 3D city model on Internet. The
paper presented a layer-combined (LC) model for city
building model. Generally the data structure of GRID model
(a kind of the DEM model) is sample and the terrain of city is
plainness, so the GRID model is used to construct the city
terrain model.
The following sections are arranged as follow. Firstly, in order
to view the 3D city data, building the 3D-city model is needed. A
layer-combined (LC) model for city building model and GRID
model for city terrain model are presented. Secondly, the
system architecture for visualization and query, presented here,
is typical client-server architecture. In order to speed up the
operations with the query analysis and fly over the three-
dimensional city scene, use of the R-tree organization of 3D
objects at the database on the server-side. Finally, an
application system (CWeb3D) for 3D-city model on Internet is