Design And Research Of Land Cover Semantic Metadata Sharing System

Global Land cover and its change are considered to be essential data and key parameters in Earth-related research such as natural resource management,climate change analysis and Earth system simulation.With the rapid development of Earth observation technology,image processing and information extraction technologies,various scales of land cover data and products are continuously produced,and corresponding analysis algorithms,application models,functional services have also been proposed.However,due to technical limitations and many other factors,these massive land cover information is released and stored in different platforms and databases around the world,the phenomenon of “information islands” is prominent.Due to the lack of sufficient metadata to describe the land cover data and services and multi-source,multi-class,heterogeneous global land cover resources are difficult to share at the same time.In this paper,the design of land cover metadata model is carried out.Then,based on this,the surface coverage metadata ontology model is proposed and constructed,and the global land cover semantic metadata sharing system is realized.The main research work of the thesis is as follows:(1)In-depth analysis of the status quo of land cover information sharing and application,research and reference to the foundations of existing national and international common metadata standards.The National Geographic Information Metadata Standard is a prototype,which combines the land cover information and the related resource characteristics in its processing application to design the land cover metadata model,through the mapping relationship between ontology modeling language(OWL)and surface overlay metadata modeling language(UML),(2)Due to the lack of semantic description ability and logical reasoning ability of metadata,when relevant personnel use the traditional metadata catalogue service to perform surface coverage resource discovery,it is difficult to obtain effective information with high matching degree and the number of related resources retrieved is small.Therefore,based on the research of geographic ontology theory,this paper constructs the land cover metadata ontology.Combined with the traditional OGC(Open Geospatial Consortium)catalogue service,the semantic directory service of land cover is proposed.(3)Designing the land cover semantic metadata sharing system from three aspects: design scheme,system architecture and functional analysis.Based on the theoretical research of(1)and(2),and with the proposed semantic catalogue service of surface coverage as the main body,the prototype system of semantic metadata sharing of land cover was developed by using Jetspeed technology.The practicability of the semantic metadata sharing system was verified by analyzing the foreground functions of the prototype system and displaying the back-end management.