The three-dimensional GIS （3DGIS） has been developed for a long time

but with the research work goes further deep

it is found that it’s almost impossible to establish a common 3DGIS platform

because objects data modeling and its spatial relationship expression is so difficult. As city is the central place that people living and information spreading

doing research of 3-dimensional urban GIS not only has great significance

but it is also one urgent problem that people want to resolve. Thus three Dimensional City Model （3DCM） research becomes a hot area in GIS field in recent years. The 3DCM research also has great significance in traffic

terra

mine

survey

and other fields

especially in city planning

construction

and environmentology. The 3DCM research has made a great progress in Japan

Germany

Austria

Canada and China. The 3DCM researches have been done abroad

and many works are largely related to specific applications.In addition

people still have no common understanding to 3DCM concept and its research meaning. In this paper

the authors consider that the `3-Dimensional City Model’ is a suitable concept

and 3DCM content meaning should include: various 3D entities data modeling

huge data management

3D spatial relationship expression and operation

3D spatial data storage

manage and query

and large city area real-time visualization etc. To 3DCM theory research works

methods used in data modeling could be classified into three types: method based on DEM and images

method based on primitives and 2DGIS

and method based on 3D data structure. For data management

the majority of systems are still using 2DGIS

while 3D expression only used in 3D visualization

and few systems manage and express 3D objects using 3D expression in its fundamental. At present 3DCM mainly uses CAD to establish objects model

and 2DGIS has managed a large number of data

so the main research works focus on 3D data and texture capture

as well as 3D objects reconstruction based on images. Although 3DCM research works have got a rapid progress

many problems still exists

e.g.

data modeling needs further research works. Present model could only express regular 3D entities

and it’s difficult to express complex 3D entities. At the same time

present 3DCM system could only provide animation and fly functions

and many research works still need to be done in side of spatial query and spatial operation.