A conceptual framework for middle-up-down semantic annotation of online 3D scenes

Semantic metadata has many uses in online virtual environments, but the technology for acquiring and managing metadata is not yet fully developed. This paper presents a partial solution that combines and extends traditional top-down and bottom-up approaches to semantic annotation. The paper proposes a metadata architecture composed of three layers, each of which has a metadata store and an interface for importing metadata from a specific group of providers. Under certain conditions, metadata can be propagated between layers, enabling it to be shared with other users of the same application or other applications based on the same virtual reality model. A proof-of-concept implementation demonstrates the feasibility of implementing the architecture using realXtend, an open platform for online multiuser virtual reality applications.