Land Administration practices worldwide rely mainly on 2D-based systems to define legal and other spatial boundaries related to land interests. However, the built environment is increasingly becoming spatially complex. Land administrators are challenged by an unprecedented demand to utilise space above and below earth's surface. The relationships between people and land in vertical space can no longer be unambiguously represented in 2D. In addition, the current societal demand for sustainability in a collaborative environment and a lifecycle-thinking, is driving the need to integrate independent systems with standalone databases and methodologies, associated with different aspects of the Spatial Development lifeCycle (SDC). Land Administration Systems (LASs) are an important component of the SDC. Today, a LAS is often mandated and managed as a domain in isolation. Interaction and data reuse with the other phases of the SDC is limited and far from optimal. It is expected that effective 3D data collaboration, sharing, and reuse across the sectors and disciplines in the lifecycle will enable new ways of data harmonisation and use in this complex environment; will improve efficiency of design and data acquisition, as well as data quality (in relation to specific regulations); and will minimise inconsistencies and data loss within information flows. Overall, a cross-sectoral approach is directed towards improving the current state of the Land Administration (LA) domain. This paper consists of two parts. In the first, a review of the current situation, with respect to LASs is presented, concluding the needs for improvement in terms of effectiveness and consistency. In the second part, the vision for the future of LASs is introduced in a wider context, and as an important phase in the SDC, with regards to legal, technical, and organisational aspects. In this part, the needs and considerations that result from the evolving environment and the emerging technological advances are addressed, with a view to discussing a cross-sector approach to collect, maintain, reuse, and share 3D data. In such a cross-sectoral approach, various interoperability issues appear, making it necessary to introduce and use standards. In this respect, the ISO 19152:2012 Land Administration Domain Model (LADM) in its current Edition I, as well as in Edition II (expected in 2022) may serve as the standardised core structure of a 3D LAS, with respect to its role as further presented in this paper. In parallel, the evolution of the Building Information Modelling (BIM) in the design and construction industry, as well as the fact that BIM plays a central role in the life cycle of development projects, are well recognized. Emphasis is given on feasible reuse of BIM/IFC (Industry Foundation Class) data in a 3D LAS. Those considerations are addressed through a web-based system architecture for a future 3D LAS, thereby attempting to integrate heterogeneous systems in the SDC.@en

Background: Over the last years, the new role of Land Administration in realising the Information Infrastructure and the need to address spatial and non- spatial land related data exchange between countries emerged and since then, standard models were created and put into use. Two examples of these standards are the Land Administration Domain Model and INSPIRE's Cadastral Parcels. The former is an official international standard with a great deal of prospects; it is based on the 'people - land' relationship and has many applications apart from storing data about properties. The latter is part of a specification framework (set of rules) describing how cadastral parcels can serve as reference for creating a European Spatial Data Infrastructure, enabling cross border dissemination of data. Methods: This paper provides the design of a conceptual model in conformance with both standards. Within this context a Land Administration Domain Model - compliant country profile and the INSPIRE model for Cadastral Parcels are proposed based on characteristic cases from the Hellenic Cadastre. Applying LADM brings along the collective international expertise on various aspects, which are analysed and applied for Greece: including administrative and spatial sources, supporting historical data (versioning), integration of legal (rights) and spatial data (cadastral map), including different register types (Archaeological, Urban, Rural, Forest), and allowing for an integrated 3D registration. Results: This research results in a model that can be used as a transition from the current cadastral system to a fully LADM- compliant one, taking also into account the INSPIRE directive. The paper further investigates how the developed conceptual model, may be automatically converted to a technical model using Model Driven Architecture. Problematic issues and constraints are highlighted when applying the Model Driven Architecture approach and suggestions for resolving these issues are described. Conclusions: It is feasible to develop a conceptual model (country profile) which is in conformance with multiple standards, LADM and INSPIRE, because these are well aligned. Cross-boundary land administration is more than ever a very important requirement in todays’ global and European community. This is where the adoption of standards comes to play in realising the Information infrastructure.@en

Land Administration is a quite inter-disciplinary field involving experts and knowledge regarding legal aspects, institutional support to establish relationships between involved parties and technical support to realize it. Today, land administrators and development organizations are challenged by an unprecedented demand to utilise space above and below earth’s surface, which mandates the use of 3D information. At the same time, the current societal demand for sustainability, is driving the need to integrate independent systems with standalone databases with different aspects of buildings in their lifecycle phases. In parallel, the evolution and applications of Building Information Modelling (BIM) towards integrated sustainable design and dissemination of information is gaining ground at international level. The requirements for more circular design thinking and digitalisation through technologies such as BIM can pave the ways for incremental step changes to achieve collaboration within building’s lifecycle and strategic design for decision-making. The impact of BIM on land administration domain is recognized, and it is being seen from governmental perspective as a digital reform and transition that will bring together technology, process improvements and digital information, to radically improve project outcomes and asset operations. One of the strong characteristics of BIM is that it is considered as a strategic enabler for improving decision-making and delivery for both buildings and public infrastructure assets across their whole lifecycle. In this scene, taking into consideration the continuing increase of BIM/ IFC files, recent research focuses on the potential role of BIM in the context of circular economy and circular design, and the reuse of BIM/ IFC files in buildings’ lifecycle. This paper presents an initial analysis on a BIM-based approach to support the registration of 3D property information. The research introduces the concepts and significance of circularity thinking and lifecycle approach at an era where there is mass amount of information, that needs to be handled efficiently. To this end, an extensive literature review on standardization approaches regarding BIM at international and national level is presented, followed by a state-of-art in the field of BIM exploitation as input for land administration purposes.@en

Cadastral surveying involves the delineation of property boundaries and the extent and documentation of easements and restrictions (imposed by private or public law), forming the foundation for Land Administration (LA). Survey models and processes constitute vital parts of Cadastres and Land Administration Systems (LASs). However, these models are often inadequately documented and lack standardization in practice. To address the global diversity and complexity of legal and administrative challenges in LA, standardization efforts have yielded the ISO 19152:2012 (ISO, 2012) Land Administration Domain Model (LADM), the Global Land Tool Network's (GLTN) Social Tenure Domain Model (STDM), and the OGC LandInfra/InfraGML standard. The current edition of the LADM focuses on standardised conceptual modelling of LA-related information, including a dedicated sub-package for Spatial and Surveying representation. As part of the ongoing LADM revision, a refined survey model is being developed to support a broad range of surveying and data acquisition approaches and levels of accuracy. Recognizing that surveying technology is not bound by national practices and regulations, this paper focuses specifically on the surveying aspect of LADM. It illustrates that the proposed refined survey model is applicable not only to conventional real property formation but also to participatory land rights recordation processes. The approach adopted in this research is technology-neutral, accommodating the ongoing evolution of surveying technology. It offers support for a broad range of surveying and data acquisition approaches, with varying levels of accuracy. As the demand for high-precision positioning has been persistent within the land mapping and surveying community, particularly since the initial adoption of GPS, aiming to achieve centimetre-level accuracies (initially confined to local services), the paper addresses the fundamental principles of the High Accuracy Service (HAS) concept within the proposed model. The main results presented in this paper are the conceptual model of the refined survey model of LADM Edition II (ISO19152–2), as well as an abstract, reference, cadastral surveying workflow following the principles of the proposed model.@en

Cadastral surveying involves the delineation of property boundaries and the extent and documentation of easements and restrictions (imposed by private or public law), forming the foundation for Land Administration (LA). Survey models and processes constitute vital parts of Cadastres and Land Administration Systems (LASs). However, these models are often inadequately documented and lack standardization in practice. To address the global diversity and complexity of legal and administrative challenges in LA, standardization efforts have yielded the ISO 19152:2012 (ISO, 2012) Land Administration Domain Model (LADM), the Global Land Tool Network's (GLTN) Social Tenure Domain Model (STDM), and the OGC LandInfra/InfraGML standard. The current edition of the LADM focuses on standardised conceptual modelling of LA-related information, including a dedicated sub-package for Spatial and Surveying representation. As part of the ongoing LADM revision, a refined survey model is being developed to support a broad range of surveying and data acquisition approaches and levels of accuracy. Recognizing that surveying technology is not bound by national practices and regulations, this paper focuses specifically on the surveying aspect of LADM. It illustrates that the proposed refined survey model is applicable not only to conventional real property formation but also to participatory land rights recordation processes. The approach adopted in this research is technology-neutral, accommodating the ongoing evolution of surveying technology. It offers support for a broad range of surveying and data acquisition approaches, with varying levels of accuracy. As the demand for high-precision positioning has been persistent within the land mapping and surveying community, particularly since the initial adoption of GPS, aiming to achieve centimetre-level accuracies (initially confined to local services), the paper addresses the fundamental principles of the High Accuracy Service (HAS) concept within the proposed model. The main results presented in this paper are the conceptual model of the refined survey model of LADM Edition II (ISO19152–2), as well as an abstract, reference, cadastral surveying workflow following the principles of the proposed model.@en

The growing recognition and influence of the ISO 19152:2012 Land Administration Domain Model (LADM), is revealed by the multiple country profiles that have been developed based on the standard in various jurisdictions across the world. The ongoing revision of the LADM Edition I, initiates discussions related to the development of country profiles, as well as considerations regarding their maintenance. Till today, various approaches for creating LADM-based country profiles have been followed. This resulted in the creation of an interesting mosaic of country profiles’ developing methods, with parts to be exploited and an outline of the basic steps of the development provided. Based on this knowledge, the aim of this paper is to design a methodology for the development of LADM country profiles, expected to become part of future version of the ISO 19152 LADM, the Edition II. Collective experience from good practices in the development of profiles based on LADM Edition I reported in the literature have been reviewed and used as basis for a qualitative comparative analysis. For this purpose, a set of six characteristics/criteria was developed based on key publications selected through experts’ consultation. The characteristics are generic and can be applied to all the country profiles, as well as they refer to the lifecycle of the development and implementation of a country profile, taking into account legal, institutional and technical issues. Characteristics regarding the scope of country profiles are also considered. Given this context, the design of the methodology to develop LADM-based country profiles is presented, structured in three phases: scope definition, profile creation and profile testing.@en

Intense exploitation of land implies the development of multi-level, multi-purpose, overlap-ping and interlocking structures on 3D space, thus resulting in complex, stratified, 3D real property rights between individual owners, as well as restrictions. Legislation regulates the ownership status and use of land by imposing restrictions known as Public Law Restrictions (PLRs). PLRs extend to various fields and various legislative frameworks, such as the protection of archaeological sites, protection and maintenance of underground infrastructures and utilities, environmental protection, flying of unmanned air vehicles, etc. PLRs are usually investigated in the context of property rights and restrictions in the various Land Administration Systems worldwide, and do not often gain specific attention. However, it is noticed that the restrictions that arise from Public Law need to be investigated and classified, so that they can be better utilised in the property status of land ownership. This review paper investigates the legal statutes on PLRs within the context of 3D land administration and the stipulations used to provide unambiguous modelling of PLRs, as provided by the relative literature. Moreover, the PLRs applied in the 3D space, to clearly depict rights, restrictions and responsibilities on the relevant spatial unit (land, air, marine parcel, mine, utility network, etc.), are particularly examined. Therefore, this work is to critically review and assess the aforementioned approaches on PLRs’ registration, modelling and organisation, as provided by a literature survey, and provides an overall view of the requirements and challenges within the development of 3D Land Administration Systems also considering standardisation developments.@en

The massive developments and uses of high-rise buildings indicate that the demand for use of space above and below the ground surface is rapidly increasing in recent years. The same applies to Greece, where the existing cadastral model does not cover the 3D needs and does not conform to international standards. In this paper, a model is proposed, considered as an effort for overcoming these shortcomings, based on international standards, including the representation of a wide range of different types of spatial units, organized in levels according to the LA_Level structure of ISO19152 LADM. It is a proposal for a comprehensive multipurpose LAS supporting 2D and 3D cadastral registration in Greece. A prototype system was developed to exploit the strengths and limitations of the proposed conceptual model, as well as to investigate the efficiency of technological tools. Experience from the prototype will be used to further improve the conceptual model. The steps that were followed were: the description of the prototype in UML diagrams, the implementation via INTERLIS, a Swiss standard modeling language for geodata exchange, the selection of the most appropriate technical model/format to implement and visualize the result in 3D environment and finally the conversion and/or creation of sample data into the model. In this paper it is explored how INTERLIS can be used in actual implementation of land administration system based on LADM. During the development of the prototype many design decision have been taken and these are then analyzed, together with technical problems and challenges for future work.@en

The wider recognition and use of ISO 19152 LADM Edition I, is mainly documented through the country profiles that have been developed in multiple jurisdictions across the world. Various approaches for developing country profiles have been followed, without acting in accordance with a specific (official or unofficial) roadmap or methodology. This has resulted in an interesting mosaic of country profiles, which at the same time, highlights the need to outline the basic steps that need to be followed in order to develop a country profile. Currently, the revision of the LADM Edition I is ongoing, and the discussion for the development, maintenance and update of the existing and future LADM-based country profiles has been initiated. Therefore, it is considered a good timing to address the experience gained from the developed country profiles and introduce methodological steps for the development of country profiles. This paper reflects on the country profiles that have been developed so far, identifying similarities and discrepancies on the path followed, bearing in mind the scope and objective of the development of those profiles and their level of maturity, also conforming to the land registration system and national jurisdiction. Thus, the paper is separated in three main parts: the first part that introduces the LADM revision and its scope, reflects on the existing country profiles and outlines the components of the proposed methodology. The second part presents an LADM-based country profile for Malaysia, as an example application of the proposed methodology. Finally, the last part is dedicated to the discussion, conclusions and proposals for future steps in the context of LADM revision.@en

The Land Administration Domain Model (LADM) is one of the first ISO spatial domain standards, and has been proven one of the best candidates for unambiguously representing 3D Rights, Restrictions and Responsibilities. Consequently, multiple LADM-based country profile implementations have been developed since the approval of LADM as an ISO standard; however, there is still a gap for technical implementations. This paper summarizes LADM implementation approaches distilled from relevant publications available to date. Models based on land administration standards do focus on the legal aspects of urban structures; however, the juridical boundaries in 3D are sometimes (partly) bound by the corresponding physical objects, leading to ambiguous situations. To that end, more integrated approaches are being developed at a conceptual level, and it is evident that the evaluation and validation of 3D legal and physical models—both separately and together in the form of an integrated model—is vital. This paper briefly presents the different approaches to legal and physical integration that have been developed in the last decade, while the need for more explicit relationships between legal and physical notions is highlighted. In this regard, recent experience gained from implementing INTERLIS, the Swiss standard that enables land information system communications, in LADM-based country profiles, suggests the possibility of an integrated LADM/INTERLIS approach. Considering semantic interoperability within integrated models, the need for more formal semantics is underlined by introducing formalization of code lists and explicit definition of constraints. Last but not least, the first results of case studies based on the generic LADM/INTERLIS approach are presented.@en

Dense urbanisation has led to an increasing demand and pressure for land development, resulting in the partition of 3D space into different owners sharing delimited property interests on, above or below the land surface. Consequently, cadastral spatial units range from simple, but most common, 2D, to complex 3D collections of spaces worldwide, that are more difficult to handle in terms of surveying, storing in a database, maintaining, visualising, etc. Subsequently, this asks for the categorization and organization of the different types of spatial units that are physically identified and legally recognised in various jurisdictions worldwide. In the context of the Land Administration Domain Model (LADM) (ISO 19152, 2012), the “level” concept (LA_Level class) provides a framework for organising the different types of spatial units. Based on that, five levels of encoding are defined in ISO19152, providing a framework of categorisation of 2D spatial units, represented by five spatial profiles included in Annex E of ISO 19152. Six years after the publication of the first edition of LADM as ISO standard, a lot of research has been carried out by experts from all over the world, and today, the ground seems to be mature for the LADM (edition I) revision, which started in May 2018, as a joint activity with many stakeholders involved (ISO TC211, OGC, FIG, etc.). One of the goals of the revision, among others, is to improve LADM’s current 3D support. This can be achieved through the design of new 3D spatial profiles for the different types of spatial units that are recognised by cadastral authorities in various jurisdictions. New and different 3D spatial units’ types may be considered for inclusion in the standard. To this end, the aim of this paper is to investigate, examine and review - in the context of LADM revision- the different types of real-world spatial units, as they have initially been organised by Thompson et al (2015). Based on the revised taxonomy, spatial profiles for the spatial units’ categories are introduced and (several) are further explored and designed. Hence, the focus on this paper lies on two levels: the taxonomy and the spatial profiles, while the level of encoding is not included in the scope of this paper. However, the investigation of the technical encodings that will be used for the implementation of the 3D spatial profiles is introduced at the paper as future work, underlying its importance. Within this concept, the scope and ambition of LADM revision are discussed.@en

Legal relations applying to land are of significant importance for land administration. Such relations include Rights, Restrictions and Responsibilities, deriving both from Private and Public Law. However, only the former are normally registered within cadastral systems, while the latter are either not required to be registered, or are registered to individual, thematic registries. Restrictions deriving from Public Law are gradually increasing in number and complexity, and impose significant impacts on land management, thus introducing the need of systematically organising and registering them. Standardisation is considered a means of fulfilling this aim, as it provides a common framework within which, consensus among different stakeholders on a specific process or product is achieved. Within the field of land administration, the international Land Administration Domain Model (LADM) standard plays predominant role in standardising legal relations between beneficiaries and land parcels. Therefore, this paper aims to investigate the integration of Public Law Restrictions’ (PLRs) requirements, within the LADM context. As a first step, the PLRs are recognised and classified. Next, in relation to modelling based on LADM concept, three approaches are considered: 1. within the Administrative Package by adding subclasses for PLRs to the LA_Restriction class, 2. within the SpatialUnit Package by adding new specialisations and subclasses to the LA_SpatialUnit class (also extending the code list LA_RestrictionType with PLR types) and 3. again within the SpatialUnit Package, but by using the “level” concept of LADM and the class LA_Level (also extending the code list LA_RestrictionType). The different modelling approaches are identified and presented considering modelling efficiency, UML models’ complexity and extensibility, while the proposed modelling approach can be considered for further extending and refining the current LADM legal concept, to include PLRs in the context of its revision. After initial considerations, such as model clarity, completeness, but also model simplicity, the authors opted for the third approach, as the one that best fits the purpose of PLR standardisation, which is then further analysed in more detail. Challenges regarding standardisation of PLRs within the LADM context, are also addressed, with regards to the on-going LADM revision process.@en

Standardization in land administration domain has been expanded to 3D and even 4D representations, adopting a multipurpose character, in order to become the foundation of a sustainable and smart economic development. At the moment, although the potential benefits of 3D Cadastre is argued to be enormous and there are plenty of standards related to 3D Cadastre while others enhancing the role of 3D Cities, there is no complete solution for 3D Cadastre. That being so, the last years, there has been a rapid increase in the integration, harmonization and implementation support of such standards. In this context, the integration of 3D legal spaces with 3D physical objects is gaining ground, as the (invisible) legal boundaries do not always match with the physical counterparts, leading to obscure situations. LADM, the International Standard for land administration, was proved to be one of the best candidates to unambiguously represent 3D Rights, Restrictions and Responsibilities. On the other side, spatial data models and virtual city models manage 3D urban structures without focusing on legal aspects. Many researchers have explored integrations between those aspects giving promising results. In this direction, apart from international standards, also national standards have been developed to enable the communication between land information systems. One of the most representatives is INTERLIS, a Swiss standard, a precise, standardized Object Relational modelling language on the conceptual level, which allows for automated quality control. Thus, in this paper the focus is given on how INTERLIS and LADM complement each other in the actual implementation of land administration systems. Main challenges among others in the context of this research include: 1. extensible hierarchical and versioned code lists in INTERLIS models, 2. formally define LADM constraints in INTERLIS, 3. discuss 3D geometry types and 4. introduce a holistic LADM/INTERLIS approach for country profiles.@en

Building Information Models (e.g. BIM, IFC) and virtual 3D city models (e.g. CityGML) are revolutionising the way we manage information about cities. The main focus of such models is on the physical and functional characteristics of urban structures (Aien et al, 2015). On the other hand cadastral data models, (e.g. Land Administration Domain Model (LADM)), have been developed for legal information modelling and management purposes without providing correspondence to the object’s physical counterperts. 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. In order to examine the correlation between those aspects, a prototype system was developed based on model driven architecture practices, empahasizing in formalization of constraints. Constraints have been proved effective in providing solutions needed to avoid errors and enable maintenance of data quality; thus the need to specify and implement them is vital. The paper explores possibilities of linking 3D legal right, restriction, responsibilities (RRR) spaces, modelled with LADM (LADM, ISO 19152), with physical reality of 3D objects (described via CityGML, IFC, InfraGML, etc). During this implementation, INTERLIS, a standard modelling language for geodata exchange, was selected as modelling language, because of its claimed good support of constraints in vendor neutral manner and ease of obtaining actual implementation. The system’s development cycle, from conceptual model to implementation of working prototype is illustrated through a proposed model for a Multipurpose Land Administation System (MLAS) for Greece. The prototype is developed in order to evaluate the strengths and limitations of the proposed conceptual model, as well as to investigate the efficiency and limitations of the existing technological (INTERLIS) tools. The process followed during the prototype development is cyclical and repetitive, providing feedback to the initial model during all the stages and improving it in terms of efficiency, reality and technical implementation. Main challenges among others during the system’s development cycle include the following: 1. how to express various LADM constraints (OCL and semiformal in standard) formally in INTERLIS, 2. how to include extensible hierarchical code lists in INTERLIS models (not natively available) and distinguish them from enumeration values, 3. how to model 3D volumetric primitives in INTERLIS (not natively available) and 4. how to link two models (legal - physical) using cross domain constraints. @en

Intense exploitation of land in the vertical direction has brought up complex legal relations between different types of spatial units with various characteristics (e.g., land, marine, air, underground parcels, and infrastructure objects). Therefore, the use of 3D models is required to clearly represent real property and associated Rights, Restrictions and Responsibilities (RRRs), deriving both from Private and Public Law. The latter are either not registered to cadastral systems (i.e., in The Netherlands very few have been registered like the private natural beauty areas, as they came with tax benefits), or are recorded to individual, thematic registries. Public Law Restrictions (PLRs) impose significant impact on ownership rights and land management, thus requiring to be systematically organized and registered. This brings out issues of identifying which types of PLRs need to be registered (based on land administration policies that apply in each country/ jurisdiction), selecting and “spatializing” them (in 2D/3D/nD). Within the field of land administration, the ISO 19152:2012 Land Administration Domain Model (LADM) plays predominant role in standardizing legal relations between parties (people) and spatial units (land). LADM is currently under revision with its second edition widening its scope as a multipart standard comprising 6 Parts. The revision of LADM stimulates discussion on new concepts that could be included at the Edition II, and possibilities of refining the existing ones. In this context, the paper investigates the option to model PLRs into the multipart standard and investigates how to optimally categorize them based on the LADM Edition II Parts. The paper builds on previous work by the authors and aims to propose a flexible framework to model PLRs at conceptual level in the context of LADM Edition II. To validate the modelling proposal, two case studies of PLRs are studied. The first one relates to the restrictions imposed on land parcels crossed by the Trans Adriatic Pipeline (TAP) in Northern Greece, and they refer to the establishment of protection zones, where construction and agricultural restrictions apply. The second case study refers to land use restrictions in the vicinity of an archaeological site in the municipality of Patras, in southern Greece. Those use cases were selected because of their generic character that may apply to other countries/ jurisdictions, regardless of legal framework differences.@en

The last decade, significant progress has been made in advancing the concept of 3D Cadastre and related technologies to facilitate its realisation. There are many examples of partial implementation and prototypes of 3D parcels registration around the world as stated by Kitsakis et al (2016) and Dimopoulou et al (2016) regarding selected countries. While standardisation in the land administration domain extends to 3D and even 4D representations, currently, there is no country that has a fully operational 3D Cadastre supporting all stages of the registration and dissemination (Van Oosterom et al, 2014). In the context of 3D Cadastre developments worldwide, the Land Administration Domain Model (LADM), ISO 19152, outlines the foundations for a 3D Cadastre and becomes one of the best candidates for unambiguously representing 3D Rights, Restrictions and Responsibilities (Kalogianni et al, 2017). The spatial development life cycle of an object begins outside the cadastral registration cycle and has a direct impact on how a specific development application is processed. Thus, in considering the changes required to allow a jurisdiction to register 3D objects, it is important to note the sphere of influence that could have an impact on 3D registration. These include multiple stakeholders and processes, which generate different user needs, as addressed at the previous section and also new opportunities that could be addressed on the current LADM version. To this purpose, this paper explores the needs and prospects towards further 3D modelling of the present LADM version, as derived by the current LADM experience in various countries worldwide in the context of the full spatial development cycle. Nevertheless, over the last few years the number of jurisdictions that are developing LADM-based country profiles, prototype systems and undertaking pilots using various physical models and data formats to achieve LADM implementation in the context of 3D Cadastre has become more significant. Those approaches can be mainly categorised as “fully operational” implementations and “partly-operational” implementations focusing on different aspects of 3D cadastre development cycle; e.g. submission of 3D survey plans, prototype stage; implementations that focus on visualisation, implementations that focus on constraints and validation rules, etc. Finally, within this context, this paper examines how current LADM version can efficiently meet the needs stated above and update user requirements for LADM in the context of the upcoming revision.@en

The origin of surveying has a close connection with the designation of land boundaries, while cadastral surveying is a means of defining the limits of properties, thus forming the basis for land administration, serving as an important tool to gather, assess, and update geographical spatial data. Accurate description and record of land are the fundamentals to their rational use and conservation and form the core of wellestablished Land Admini stration Systems (LASs). Although surveying models and approaches are important for Cadastres and LASs, they are not always documented in detail, while with the rapid advances in technology and geoinformation they need to be revised quite often. The ISO 1 9152:2012 Land Administration Domain Model (LADM), which focuses on standardised modelling of information at the conceptual level, has a dedicated sub package for Spatial and Surveying representation. The first edition of the standard provides multiple spa tial representations, and the ongoing LADM revision shall support a broad range in surveying and data acquisition approaches and accuracies, considering the evolution of technology and the encodings used in practice. A conceptual model of the refined surve y model is expected to be included in Part 2 of the new edition of the standard, while its technical implementation(s) covering both 2D and 3D boundaries in Part 6. This paper aims to present the fundamentals of the refined Survey Model of LADM Edition I considering the need to support the interconnection with the everI, evolving surveying methods and acquisition techniques in a standardised way, including among others the Galileo High Accuracy Services requirements and the alignment with other standards, as well as participatory methods. One of the standards which synergy with LADM is investigated in this paper is the OGC LandInfra, and specifically Part 6 “Survey”, that provides a framework for information about observations, processes and their results collected during survey. The development of the proposed model was informed by two case studies using survey plans according to Danish practice and cadastral data from the Hellenic Cadastre.@en

Among the topics that are introduced and/ or being refined in the context of the revision of the LADM 19152:2012, the legal Land Administration-related aspects are being investigated. With the knowledge and the experience from the developments of the LADM so far, and the ongoing discussion between the parties involved in the standardisation process, the need to clarify certain legal land-related aspects and to examine the alternatives for further refinement is highlighted. Therefore, this paper presents prior work on LADM-related legal aspects since the vote of LADM as ISO standard (2012), till the time of the preparation of this paper (2021) to report the necessary background for this research. This concerns the developments related to the various legal refinements that have been proposed during this time period and specifically the refinement of the legal profiles, the LADM functional support to representation of both statutory and customary tenure and the work regarding the explicit definition of restrictions that arise from Public Law. Moreover, this paper focuses on documenting the proposals on a refined legal model for the LADM Edition II. These include the following: (a) more detailed classification of RRRs, based on the two major types of interests in land: privately agreed interests as well as regulations imposed by a public agency and Public Law restrictions. The paper also includes (b) a discussion on the extent that LADM Edition I provides efficient support for the title and deed registration systems (as others e.g. in socialist environment), as well as (c) a discussion on how restrictions and responsibilities can be modelled as rights’ relationships between an owning and a benefitting Party. @en

The content of this Special Issue has its origin at the “5th International FIG Workshop on 3DCadastres”, organized in Athens, Greece, 18–20 October 2016. The Workshop provided a further stepping stone to identifying key issues and challenges within 3D Cadastres developments, as well as exchanging ideas and solutions between scientists from academia, industry, and government. After the workshop, authors of selected papers (or in some cases, two teams of authors of related papers) were invited to publish in this Special Issue, which is devoted to the legal, organizational, and technical aspects of 3D Cadastres. Therefore, this Special Issue is where practice and research meet, influence, stimulate, and support each other, showing the progress in the key areas of 3D Cadastres, including the legal framework of 3D Cadastres, initial registration of 3D parcels, 3D data management, visualization, distribution, and delivery of 3D parcels. The 13 papers published in this Special Issue are the end result of the authors’ hard work and a rigorous journal’s peer review process. We would like to thank the authors for their valuable contributions and of course express thanks to the IJGI Editorial Office and the reviewers for their thoughtful suggestions and constructive criticism. Even though all papers in this Special Issue stand on their own, depending on cultural, geographical, and technical differences, we have tried to produce a rather holistic approach, covering this field of research. Moreover, we have highlighted similarities and dissimilarities in addressing important 3D Cadastral topics, as follows.@en