Conceptual Model Supporting a Range of 3D Parcel Representations Through all Stages: Data Capture, Transfer and Storage
Rodney Thompson, Peter van Oosterom et al.
The complexity of volumetric spatial units is highly variable, but in practice the vast majority are composed of simple components. Even where the spatial units are apparently complex, most boundary faces of real cadastral spatial units are either vertical or horizontal, and a significant majority of spatial units are composed of a simple polyhedral slice - a prism resulting from the vertical extrusion of a 2D polygon. A categorization of volumetric spatial units recognizing this aspect was proposed earlier (Thompson, van Oosterom et al. 2015). Further, the ISO19152 - Land Administration Domain Model (LADM) recognises that even conventional 2D spatial units are, in the real world, prismatic columns of space defined by vertical faces, with no explicitly stated upper or lower boundary faces. These are known as ?Face Strings? (LA_BoundaryFaceString). This paper explores an integrated method of defining 3D spatial units, whereby the ?footprint? of the spatial unit is represented as a LA_BoundaryFaceString, associated with a (possibly empty) set of more general faces (each stored as a LA_BoundaryFace). This representation fits within the LADM (ISO-TC211 2012) and is suitable for practical encoding formats. It is shown that this provides a complete encoding scheme - from simple 2D land parcels, to the most complex volumes. It is further shown that this scheme is more parsimonious in storage than the conventional polyhedron (stored as a collection of faces) for the vast majority of real cases (using real world examples).
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