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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
emphasize particularly on microcosmic (that is, one the city). 
Digital city’s content and frame detail are presented in table 1. 
Infrastructure 
Network Level 
Wide Band Wire Network: 
Internet, WWW, Great 
Grid; 
Wide Band Wireless 
Network: Mobile Internet, 
WAP, blue tooth, Mobile 
GGG; 
Wide Band Integrated 
Network: Mob, Web, GGG 
Data Level 
Primary Geodata: DEM, 
DLG, DRG, DOM, 
Infrastructure Data: City 
Constructing, Traffic, 
Energy Sources, 
Communication, 
Social, Economic, Cultural 
Data: Population, Resource, 
Economy, Culture, 
Education, Science, 
Technology 
Level 
Spatial Information 
Technology Platform: RS, 
GPS, GIS, VR, WebGIS, 
Management Information 
Technology Platform: ERP, 
CRM, SCM, 
LBS(WebMIS), 
Integrated Information 
Technology Platform: 
Web(GIS+MIS), 
Guarantee 
Level 
Standard and Specification, 
Security, Supervision and 
Evaluation, 
Policy and Code, 
Education, 
Application 
Engineering 
Management 
Level 
Management about City 
Planning, Traffic, Power, 
Communication, Accident, 
Application 
Level 
e-Govemment, e- 
Commerce, e-CBD, e- 
home, 
Service Level 
Public Information, Mobile 
Information, 
Decision-making, 
Table 1 Digital City’s Content and Frame 
2.3 Architecture of Digital city 
The construction of digital cities is an integrated application of 
modem technologies. Those technologies are Internet, 
communication, grid computing, spatial information grid, 
Global Positioning System (GPS), Geographical Information 
System (GIS), Location-Based Service (LBS), Data Mining, 
Virtual Reality, etc. But spatial data infrastructure is its 
foundation including a variety of databases, such as spatial 
database, image data database, geocoding database, population 
database, resource database etc. In the middle tier, there are 
some functional servers, for example, spatial data server, spatial 
routing and gateway server, geocoding server, attribute data 
server. The architecture of Geo-information system is shown in 
Figure 1. 
Figure 1 Architecture of Digital city 
The hierarchical stmcture of Geo-information system includes 
mainly five levels, namely the technical level, the data level, 
the management level, the service level and the application 
level. The technical level involves the technical innovation, 
support and guarantee system. The data level includes the 
spatial data acquisition, database construction and updating. 
The management level indicates the information conformity, 
integration and navigation system. The service level is the 
socialization and industrialization application service system. 
The application level mainly consists of public service, 
government affairs and other applications. The authors explain 
the five levels as follows: 
Application level: realize all kinds of applications involving 
government, the enterprise and individuals, constitute spatial 
application infrastructure; 
Service level: realize services and applies involving spatial 
information sharing, constitute spatial service infrastructure; 
Management level: realize the integration, fusion and 
management of multiple source spatial information, constitute 
spatial information infrastructure; 
Data level: realize spatial data acquisition, database 
construction and updating, constitute spatial data infrastructure; 
Technical level: investigate technical innovation, support and 
guarantee system, constitute spatial information grid 
infrastructure. 
On microscopic level it is used for spatial datum frame system, 
spatial data processing service system and the foundation of 
spatial database. Based on the spatial datum frame, the GPS 
continual tracking facility and the difference datum station can 
be additionally built, which carries or processes GPS data or 
broadcasts to the public.