A Unified 3D Spatial Data Model for Surface and Subsurface Spatial Objects
AbstractThree Dimensional (3D) spatial modelling is an abstract representation of reality using mathematically proven relationships defined as points, lines, polygons and solids to represent man-made and natural features above, on and below the surface of the earth. 3D topology is the interrelationships existing between these objects to enable visualization, query and analysis. 3D mod-elling of subsurface objects and their integration with the surface and above surface objects currently lags behind despite efforts of researchers and the attempt at viewing above, surface and subsurface man-made objects for earth realism. Level of Details (LoD) for spatial objects has been extensively studied. However, these have not been extended to man-made features below the surface. LoD maps for surface and subsurface integration exist for most city centres but the 3D component is lacking and this does not enhance the Level of Realism (LoR) in most city centres. Knowledge about the surface and subsurface 3D objects for city centres, mining and 3D cadastre will create awareness among stakeholders for effective planning of a city or mine. This paper provides a discussion for 3D surface and subsurface integration. Various 3D spatial data models currently in existence for the integration of surface and subsurface models are discussed and a geometric, topological 3D object oriented model is sug-gested. A UML diagram for the top hierarchy class is presented and a conceptual and logical model for surface and subsurface integration is also discussed. A simulation of the above, on and below 3D spatial models for man-made constructions at differ-ent LoDs is presented. A simulation of this with regards to mining and cadastre is also presented. The model presented can be adopted in realising 3D GIS for mining and 3D cadastre can be realised in Ghana. Further work is geared towards 3D spatial analysis for such an integrated model.
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