Semantic Description of 3D Environments: a Proposal Based on Web Standards

While the number of virtual environments available on the net is constantly increasing, most of them are composed by a wide number of low-level geometric objects that lack any semantic description. Such situation prevents advanced uses of the data contained inside the environments, such as selection and extraction of semantic objects or advanced queries that refer to high-level properties of the environment. Recently some attempts have been performed in order to annotate 3D environments using the descriptive capabilities of MPEG-7 standard. While the solutions proposed are interesting, there are still a number of issues to be solved, including the definition of scene-independent ontologies that can be useful in different situations (e.g., 3D world validation, semantic search through a set of worlds, etc.). This work proposes an alternate approach for associating semantic information to 3D worlds based on the integration of two web standards: the X3D language and the semantic web. The approach is characterized also by the definition of scene-independent ontologies and by the definition of semantic zones that complement the role of semantic objects for giving a complete description of the environment. In order to show the potentialities of such approach the paper will illustrate an application scenario characterized by the extraction of the semantic information from an X3D document and the associated ontology for generating a high-level and multilevel textual description of a tour through the 3D environment described by them.