TOWARDS A REAL ESTATE REGISTRY 3D MODEL IN PORTUGAL: SOME ILLUSTRATIVE CASE STUDIES

Abstract. The 3D concept emerged as a key concept within geoinformation science. 3D geoinformation has been proved to be feasible and its added value over 2D geoinformation is widely acknowledged by researchers from various fields. Even so, 3D concept merits still need to be exploited further and more specific applications and associate products are needed – such as within real estate cadastre, our ultimate field of interest. The growing densification of urban land use is consequently increasing situations of vertical stratification of ownership rights. Traditional 2D cadastral models are not able to fully handle spatial information on those rights in the third dimension. Thus, 3D cadastre has been attracting researchers to better register and spatially represent real world overlapping situations. A centralised distributed cadastral management system, implementing a 2D cadastral model, has been conceived by the national cadastral agency in Portugal: the so-called SiNErGIC. The authors seek to show with this paper that there is room though for further investigation on the suitability of a 3D modelling approach instead, which should not be confined only to topologicalgeometric representations but should also be extended in order to be able to incorporate the legal/administrative component. This paper intends to be the first step towards the design of a prototype of a 3D cadastral model capable of handling the overall multipurpose cadastral reality in Portugal; it focuses primarily on the clear identification of some case studies that may illustrate the pertinence of such an approach in the context of this country.