Browsing by Author "Siew, Chengxi Bernad"

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    Enhancement of three-dimensional geospatial web services using compression techniques
    (Universiti Teknologi Malaysia, 2016) Siew, Chengxi Bernad
    Two-dimensional (2D) Spatial Data Infrastructure (SDI) has been widely applied in various areas such as city planning, disaster management, urban navigation and urban modelling. However, three-dimensional (3D) SDI has not seen much progress: current examples of such an initiative are Berlin-3D and Heidelberg-3D, which are not fully developed. Use of City Geography Markup Language (CityGML) decreases data transfer efficiency and raises data storage issues in application such as analysis of the 3D Geographic Information System (GIS) that requires both geometries and semantics information. The efficiency determines the way spatial data being handled in SDI. For instance, small devices used for examining 3D urban models in a 3D immovable property tax appraisal exercise. CityGML data transmission for analysis purposes is impractical due to inefficiencies in terms of file size and bandwidth consumption. Currently, there is no efficient handling of 3D spatial data for either geometric or semantics information. This research investigates the existing 3D SDI use cases and frameworks, as well as XML and general compression techniques. The research also examines methods to improve efficiency by employing the proposed design with schema-awareness attached to an encoder within web services, and then proposing a generic solution for SDI development. Furthermore, the research proposes a coupling layer of encoder and decoder within web services or on the web service to client side, which is a compression and decompression tool for CityGML data transaction within 3D SDI. The implementation and analysis of this work shows that the algorithm produced a 15 per cent smaller file size for the lossless and 20 per cent to 30 per cent for the near-lossless option in comparison with the state-of-the-art Lempel-Ziv-Markov (LZMA) algorithm alone. This encoder also examines entropy of the data input and shows that the encoding process significantly reduces the bandwidth to between seven per cent to nine per cent of the original data size. The chaining of the encoder and decoder enables binary data transactions within web services while maintaining the benefit of data interoperability. The future of the research includes integrating image compression for 3D object texture and handling of 3D spatial data in small devices. The custom application network protocol could be further examined for the handling of data transactions for 3D spatial data standards in OGC web services (OWS)