Mixed 2D and 3D Survey Plans with Topological Encoding
Rodney James Thompson, Peter van Oosterom & Kean Huat Soon
There is a wide range of spatial units in jurisdictions around the world, ranging from simple 2D parcels (spatial units defining 3D column of space) to complex 3D collections of spaces, which are defined at various levels of sophistication from textural descriptions to complete, rigorous mathematical descriptions based on measurements and coordinates. The principal spatial unit to be considered in a cadastral database is the base 2D land parcel - the basic spatial unit of land that is subject to ownership or other rights by a party. There is a varying complexity of 3D subdivision of the base 2D land parcels, and a complex set of secondary interests (other RRRs), which may refer to all or part of a base cadastral 2D land parcel, or span several 2D land parcels. 3D spatial units may be defined entirely by reference to the structure which houses them (the ?building format units?), or volumetrically by the dimensions of boundary surfaces. 2D land parcels (implying 3D columns of space) or 3D spatial units may also be subdivided into smaller spatial units, with the remainder being kept as common property for the owners of the individual units. This has led to the adoption of multi-level schemes. In this paper, we explore the practicality of encoding spatial units in a way that highlights their 2D extent (as typically represented on maps, survey plans and existing cadastral databases), while fully defining their extent in the third dimension. The suggested method uses a form of mixed-dimensional topological encoding (sharing boundary definitions between adjoining spatial units) that is simple and efficient in space requirements. It prevents problems of overlapping between spatial units in 3D, while providing a data source for a mixed 2D / 3D digital cadastral database without redundancy or inconsistency.
Event: 5th International FIG Workshop on 3D Cadastres
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