Research Of Semantic Multidimensional-Index On Space Information Metadata

With the rapid development of space technology and information technology in China, the importance of spatial information metadata management is becoming increasingly prominent. However, an international standard has not come out yet, and China is also attempting to propose its metadata standard. Spatial information metadata standard has such characteristics as disunity, distributed and massive, and it makes the management, maintenance and acquisition of spatial metadata rather difficult and complicated.Spatial metadata management based on spatial information sphere does not mean to establish a new standard and has not made any modification or changes to the current standard. The purpose of it is to build a universal logic model from the angle of semantic relations of kinds of metadata standards. It will not affect the acquisition or storage of spatial metadata. And through the universal, extendable logic model, it will be easy to constructs a self-adjusting spatial information management and service mechanism and improves the usage of spatial information to a great extent.This paper have analyzed spatial metadata, pointing out that there are three features in spatial metadata, and based on these three features, this paper have developed following:(1)Many multidimensional indexes have simply made contribution to the dimensions with the type of point or interval. While considering the data set of hybrid dimensions with the type of both point and interval, there is few study to deal with the problem. This kind of data set is often applied in the metadata which describe the geographic information resources. This thesis proposes a new multidimensional index—PI Tree, adapting to this kind of data set above, using the idea of super-sphere in the SS-tree. Then, we discuss the algorithm of building and searching of our tree. Finally, we make experiments to show PI Tree outperforms the R*-tree.(2)Based on ontology techniques, this thesis has proposed multidimensional index building and retrieval methods with the help of ontology in order to solve semantic problem in spatial metadata.(3)Based on dimensional hierarchical encoding techniques, this thesis has proposed a kind of binary dimensional hierarchical encoding method in order to solve hierarchical semantic problem in spatial metadata.