3D modeling of the ownership structure of condominium units

Highlights

• An ownership structure of a condominium is presented by mapping the physical parts and corresponding legal treatments.

• A CityGML-LADM Application Domain Extension (ADE) model is proposed for the ownership structure.

• The proposed three-dimensional model can express the ownership for a condominium in more detail than the current models do.

• This study also shows that ADE in CityGML is an effective tool to develop practical spatial models for land administration.

Abstract

Existing studies on modeling immovable ownership have not explored the internal structure and internal semantic relations of the ownership of condominium units in depth. This paper suggests extending CityGML with legal concepts from the Land Administration Domain Model (LADM) via the application domain extension (ADE) mechanism of the CityGML as a feasible approach for describing the ownership structure of condominium units. Based on legislation in China, a CityGML–LADM ADE model is proposed to precisely present the ownership structure of a condominium unit, which reflects the interrelations of legal objects and their physical counterparts. Finally, the proposed model is validated by two case studies.

Introduction

Rapid urbanization has led to an increased demand for the three-dimensional (3D) use of urban land space in terms of land administration. Because various complex buildings have posed a challenge to current 2D (or parcel)-based land administration systems, 2D parcel-based systems cannot effectively support the management of property in 3D space with a more accurate mode. Therefore, 3D cadastres have been developed to meet the management of 3D land use space and 3D properties (Williamson et al., 2010, Guo et al., 2013, Stoter et al., 2013, Jazayeri et al., 2014, Karabin, 2014). This development helps meet the increasing social demand for the precise management of immovable property.

The core of administration of cadastres and properties is to explicitly and clearly register the rights, restrictions, and responsibilities (RRRs) of the property (Enemark, 2009), where the ownership is the crux of property management. Ownership is the lawful disposal of a property assigned to the people who own the property. A property has both bona fide and legal aspects (Aien et al., 2013, Jazayeri et al., 2014, Ying et al., 2014), and it is considered a compound object that combines the physical object with the legal treatment of the object. The physical object (or usable space) is the base of the ownership and other rights. The legal aspect of property is generally attached to the physical object. When a physical object is constructed with several parts, the legal treatment included in the ownership would be different and specific for these parts, and the ownership may consequently show an internal heterogeneity. This internal heterogeneity reflects the disparity of the lawful disposal of the different parts of an object and requires differentiating ownership in a property management system.

With the current abundance of information and growing stress on personal property, more precise management of property includes not only land space and the vertical spatial extent of the property but also the horizontal extent of the property and the ownership structure, which corresponds to the spatial components of the property. An ownership of a property (such as a condominium unit) may be divided into several parts that are associated with their physical structural components in terms of right homogeneity. For example, an ownership of a condominium unit may include two physical objects: the exclusively owned apartment itself and some shared space (such as elevators and corridors) with others. Furthermore, with respect to the legal spatial extent of a property in some countries such as China, even for exclusively owned objects (or spaces), the room space is physically recorded into the legal spatial extent, and a balcony (space) may be half-recorded into the legal spatial extent. Such subdivisions of ownership with legal space are critical in taxation, load, and insurance. Current cadastre management systems or property registration systems only record the ownership as a whole and do not differentiate the ownership by its internal heterogeneity.

Condominiums are a special type of property with a common or shared ground parcel. A building of condominiums is divided into private and common parts. On the one hand, an owner can dispose his own private parts according to the corresponding laws, which implies an exclusive ownership. On the other hand, the common parts and ground parcel cannot be disposed at someone's will and must be at a common disposal, which indicates a common or shared ownership. This complex co-ownership has been discussed by many authors (Çağdaş, 2013, Pouliot et al., 2011, Pouliot et al., 2013, Rajabifard et al., 2013). These studies mainly discussed the legal aspect of complexity, representing condominiums in the third dimension. The internal semantic relations of the ownership of a condominium unit have not yet been studied adequately. Such an ownership internal structure should be expressed in a spatially explicit manner to more precisely manage property.

The internal structure of a building can be clearly presented with rich semantic and 3D information due to the development of the CityGML model or building information models (BIMs). Considerable effort has been made to adopt CityGML or BIMs in the field of land administration and property management (Amirebrahimi, 2012, Çağdaş, 2013, Dsilva, 2009, El-Mekawy et al., 2014, Góźdź et al., 2014). CityGML and BIMs have proven to be a feasible means of exploring the internal heterogeneity of the ownership of condominiums and clarifying the spatial differences within the ownership. The contribution of this study lies in presenting the ownership structure by mapping its physical parts (private or common) and their corresponding legal treatments and proposing an available method to model such ownership structures by an application domain extension (ADE) of CityGML with the Land Administration Domain Model (LADM).

This paper is organized as follows: Related works are provided in Section 2. In Section 3, the legal context of condominium ownership in China is discussed and the ownership structure is presented based on spatial mapping. Section 4 presents a 3D model for the ownership structure by extending legal concepts from the LADM into CityGML, followed by two examples that demonstrate the availability of the proposed 3D model (in Section 5). Finally, conclusions are drawn and future work is discussed in Section 6.