The 3rd FIG 3D-Cadastres Questionnaire was conducted and distributed by the end of 2018, with an extended deadline of 15th of January 2019. The questionnaire survey is a part of the FIG working group 3D-Cadastres activities for the period of 2018-2022. The purpose of this survey is to prepare a comprehensive inventory of the current (2018) state of 3D Cadastres worldwide, to explore the near future (2022) plans and expectations in the field and to evaluate the progress during the past four years. Sharing and dissemination of this information, enable to improve cooperation, to learn from each other and to support future developments as well as to encourage collaboration between various countries and jurisdictions. As can be determined from the title, this is the third time that the questionnaire on 3D-Cadastres is being carried out. The first version was administered in 2010 in order to document the status of 2010 3D Cadastres and of the then upcoming 2014 expectations. This was followed by a second questionnaire in 2014 (with status of 2014 and ambitions for 2018). The previous responses (van Oosterom et al., 2011; van Oosterom et al., 2014) were analyzed and reported at earlier FIG events (Working Weeks and workshops). The structure of the 3rd questionnaire has remained rather similar. All of the sections and the numbering of the questions were preserved to allow straightforward comparison with the earlier questionnaires and identification of potential trends. A few questions have been refined for clarification and several new questions have been added at the end of the sections. In this paper the main results of the analysis of the submitted 2018-2022 questionnaire are presented together with an analogy drawn between the past and present responses.@en

In this chapter we address various aspects of 3D Cadastral Information Modelling. Of course, this is closely related to the legal framework and initial registration as presented in the first two chapters. Cadastral data models, such as the Land Administration Domain Model, which include 3D support, have been developed for legal information modelling and management purposes without providing correspondence to the object’s physical counterparts. Building Information Models and virtual 3D topographic/ city models (e.g. LandXML, InfraGML, CityGML, IndoorGML) can be used to describe the physical reality. The main focus of such models is on the physical and functional characteristics of urban structures (Aien et al, 2015). However, by definition, those two aspects need to be interrelated; i.e. a tunnel, a building, a mine, etc. always have both a legal status and boundaries as well as a physical description; while it is evident that their integration would maximise their utility and flexibility to support different applications. A model driven architecture approach, including the formalization of constraints is preferred. In the model driven architecture design approach as proposed by the Object Management Group the information model, often expressed in the form of a UML class diagram is the core of the development. This so-called Platform Independent Model (PIM, as presented in the current chapter) is then transformed into Platform Specific Model (PSM). This could be a relational database schema for a spatial DBMS (as will be discussed in the next chapter), or XML schema for a data exchange format or the structure of maps, forms and tables as used in the graphic user interface of a spatial application. Constraints have proved effective in providing the solutions needed to avoid errors and enable maintenance of data quality; thus the need to specify and implement them. This chapter explores possibilities of linking 3D legal right, restriction, responsibilities spaces, modelled with the Land Administration Domain Model (ISO 19152), with physical reality of 3D objects (described via CityGML, IFC, InfraGML, etc).@en