The core cadastral domain model

A standardized core cadastral domain model (CCDM), covering land registration and cadastre in a broad sense (multipurpose cadastre), will serve at least two important goals: (1) Avoid re-inventing and re-implementing the same functionality over and over again, but provide a extensible basis for efficient and effective cadastral system development based on a model driven architecture (MDA), and (2) enable involved parties, both within one country and between different countries, to communicate based on the shared ontology implied by the model. The second goal is very important for creating standardized information services in an international context, where land administration domain semantics have to be shared between countries (in order to enable needed translations). This paper presents an overview of the core cadastral domain model and its developments over the last 4 years. The model has been developed in a set of versions, which were each time adjusted based on the discussions at workshops with international experts and the experience from case studies in several countries of the world (Netherlands, El Salvador, Bolivia, Denmark, Sweden, Portugal, Greece, Australia, Nepal, Egypt, Iceland, and several African and Arab countries). Important conditions during the design of the model were and still are: should cover the common aspects of cadastral registrations all over the world, should be based on the conceptual framework of Cadastre 2014, should follow the international ISO and OGC standards, and at the same time the model should be as simple as possible in order to be useful in practise. Besides presenting the CCDM itself this paper represents an important new wave in geo-information standardization: after the domain independent basic geo-information standards (current series of ISO and OGC standards), the new standards based on specific domains will now be developed. Due to historical differences between countries (and regions) similar domains, such as the cadastral domain, may be modeled differently and therefore non-trivial harmonisation has to be done first. The presented CCDM is a result of this harmonisation and one of the first presented examples of semantic geo-information domain standards.Besides the three well-known concepts, Parcel, Person and Right, at the class level the model also includes immovables such as Building and OtherRegisterObject (geometry of easement, like a right of way, protected region, legal space around utility object, etc.) and the following concepts: SourceDocument such as SurveyDocument or LegalDocument (e.g. deed or title), Responsibilities, Restrictions (defined as Rights by other Person than the one having the ownership Right) and Mortgages. At the attribute level of the model the following aspects are included: SalePrize, UseCode, TaxAmount, Interest, Ranking, Share, Measurements, QualityLabel, LegalSize, EstimatedSize, ComputedSize, TransformationParams, PointCode, and several different date/times. The heart of the model is based on the three classes: (1) RegisterObject (including all kinds of immovables and movables), (2) RRR (right, restriction, responsibility), and (3) Person (natural, non-natural and group). The model supports the temporal aspects of the involved classes and offers several levels of Parcel fuzziness: Parcel (full topology), SpaghettiParcel (only geometry), PointParcel (single point), and TextParcel (no coordinate, just a description). The geometry and topology (2D and 3D) are based on the OGC and ISO/TC211 standard classes. The model is specified in UML class diagrams and it is indicated how this UML model can be converted into and XML schema, which can then be used for actual data exchange in our networked society (interoperability).