This paper proposes a new framework of managing virtual spaces based on spa
tial databases as an extension of VRML-based systems. The framework is suit
able for treating continuous virtual spaces and for managing the quality of
service (QoS) of the virtual spaces depending on user's operations and sit
uations of computer resources. Levels of detail (LoD) of 3D objects is the
most important rule for rendering scenes dynamically while managing the QoS
. This paper describes a method of managing the QoS depending on the LoD in
the form of spatial queries. An advantage of the framework is that spatial
databases can incrementally construct virtual spaces in clients using diff
erential descriptions based on VRML, that is, DVRML, proposed in this paper
. Dynamic spatial data such as avatar's movement and real-time multimedia d
ata such as videos should be shared by all participants in a virtual space
in real time. Our framework can also handle dynamic spatial data by means o
f real-time updating of some spatial objects in spatial databases as well a
s static spatial data. We developed some experimental applications based on
the framework in order to prove that it is feasible for networked virtual
spaces with video components.