This section provides a general background to the cadastre use and development followed by a discussion over the purpose and objectives of this study.
Background to Cadastre
A cadastre is a register of real estates in a country. It may be defined as a parcel based and up-to-date land information system that includes important records on land such as rights, ownerships and restrictions (FIG, 1995). In addition to that, it usually has geometric description of land parcels as well as relationships to other records that describe the value of parcels, their maintenance history and development and the nature and ownerships of interests. A cadastre is of fundamental importance to our society, since it specify the legal base of different rights of using land. Its roots can be traced back to the ancient Egypt, so it has served the societal development for a long time. During the years, the cadastre has developed to serve an increasing number of societal demands, such as the management of land and land use, legal rights, sustainable economic development and environmental planning of the city (Valstad, 2010).
The current geometric representation of cadastral information is usually based on very accurate but simple 2D representation of parcel descriptions with associated land information (Hassan et al., 2008). However, in the past decade we have witnessed an increasing amount of built-up areas as well as complexity in building construction and infrastructures, such as telecommunication networks, underground parking garages, etc. In order to promote this development and to secure the ownership and other rights associated with these facilities, the concept of 3D cadastre has been introduced. There are clear limitations for the existing 2D systems to register and accurately define ownership and legal status that modern city development require, and make the information accessible and usable for practitioners (Karki et al., 2010; Ledoux & Meijers, 2011). It is argued by Döner et al. (2011) and Stoter (2004) that for such complex structures, the creation of property rights within existing legislation does not solve the problem. There are remaining big challenges related to describing, depicting and querying the cadastre attributes in cadastral registration and applications. This actually explains the mentioned accurate description of FIG for the cadastral registration that considers the parcel as the basic unit where all cadastral information should be projected in 2D (Lemmen et al., 2009; Lemmen, 2012; ISO, 2011d).
Following the mentioned trends, a number of factors can be highlighted as drivers for the development of 3D cadastre:
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The part of the built environment sector that specializes in the design and construction of built facilities is rapidly converting its design and documentation systems to three dimensional building information models - BIM. The primary benefit of this new technology is the change from a simple representation (2D drawings), to a semantic representation, that allows virtual prototyping, measurement of performance and multi-disciplinary life cycle collaboration. The IFC Model specification is an open standard and exchange protocol and it is the only global open specification of intelligent building models.
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As a result of the increasing density of urban development, multi-storey buildings are increasingly having several different types of uses and new types of shared ownership.
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It is difficult on a 2D map to make simple operations like measuring the length, area, and volume of different spaces in the 3D property.
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On the 2D cadastral database, it is not possible to execute different spatial analysis and queries as the 3D data is not supported.
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3D visualization is not possible in most of the current cadastral information systems.
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Exploring and understanding the 3D development of properties are not easy for the owners of a complex property. Supported by the increase in private property ownership and values, this clearly contributes to hindering 3D applications on cadastral data.
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In the last decades, not only the increasing number of complex properties, but also the number of tunnels, underground parking places, shopping malls, building above roads and railways, different internal and external building installations and other multilevel constructions has turned 2D cadastral systems into an obstacle of development.
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The technological development in building information modeling (BIM) and in 3D GIS has made the 3D cadastral registration becoming feasible.