| Popis: |
With the emerging communication technology in recent years, geospatial data sharing is getting important and popular. Spatial data could be accessed and shared by various stakeholders anytime with the support of a common platform, the Spatial Data Infrastructure (SDI). Data sharing for 3D city building is getting popular using Open Geospatial Consortium (OGC) standard named City Geographic Markup Language (CityGML). Due to human readable schema, data sharing in CityGML often consumes high bandwidth and storage. Transmitting CityGML over web services without compression is not practical. As CityGML represented in Extensible Markup Language (XML) schema, XML compression seemed useful for CityGML. Conventional dictionary compressor such as WinZIP, GZip or BZip could reduce data size; however, the decompressed documents certainly produce the original file, which is still consuming large storage space. This paper discussed the existing 3D-SDI framework, compression techniques and how the schema-aware compressor is developed to achieve a higher compression ratio. The proposed compressor is tested by using Putrajaya city 3D building and results are compared against existing techniques. The results are then decompressed and compared with original 3D buildings by visualizing using CityGML viewer. The future directions are highlighted in the final section. |
