BIM-LADM AMALGAMATION — A REVIEW

: This paper discussed two International Organization for Standardization (ISO) standards, namely, ISO 19152 – Land Administration Domain Model (LADM) and ISO 16739 – Industry Foundation Classes (IFC), to identify three-dimensional (3D) multi-floor building rights. These days, it is challenging to characterize all multifunctional structures due to the increase in complex buildings. High-rise building land and property information management is recommended through building information modeling (BIM). Countries like the Netherlands, Australia, and Turkey have considered adopting BIM for their land administration. A land administration standard, such as LADM, offers better legal and physical representation in identifying the rights, restrictions, and responsibilities (RRRs) of the spatial units and stakeholders. However, LADM falls short in representing all building elements, such as semantic information and invisible functional spaces. Hence, this paper reviews incorporating additional information from BIM to create a comprehensive three-dimensional building representation including legal information from LADM. Issues and challenges also being highlighted with some recommendations for possible future works.


INTRODUCTION 1.1 The motivation
The objective of this paper is to review the amalgamation of Building Information Modelling (BIM) and Land Administration Domain Model (LADM).The integration of BIM and LADM has become a promising area for enhancing efficient land administration, including the management of 3D property ownership (Emamgholian et al., 2021;Andritsou et al., 2022;and Liu et al., 2023).For the past 10 years, LADM has been known as a standard in representing legal aspect of land administration objects encompassing land tenure, land value, land use, and land development (Enemark, 2005).However, the limitation of LADM in depicting semantic components warrants open data standard like Industry Foundation Classes (IFC) in fostering interoperability across diverse domains such as architecture development (Gursoy et al., 2022).IFC is a standard for BIM used in construction and building industry to store and exchange information on semantic materials as well as the spatial relationships between them (Eastman et al., 2011;Jazayeri et al., 2014;and Isikdag et al., 2007).BIM serves as a comprehensive digital model, capturing both the physical and functional attributes of a structure, fostering collaboration among diverse project stakeholders.However, information about ownership rights within buildings has poorly defined in BIM models (Atazadeh et al., 2016;Durdyev et al., 2022;and Brooks, 2023).
Previous works pointed to the usefulness of BIM-LADM integration where these two models could provide a betterintegrated model that enables to answer the questions on rights, restrictions, and responsibilities (RRRs).Currently, there is no collaboration between the organizations, leading to a disconnected system, different software, distinct data formats, and improper integration.Introducing LADM to support multiple pillars or organizations could lead to improved collaboration, reduced confusion, and the availability of up-todate information.People possess valuable information about a piece of land and the building's 3D aspects (BIM/IFC) which rely not only on land tenure or property ownership, but also on factors like land value and spatial planning (Indrajit et al., 2021).Combining these diverse pieces of information (LADM and BIM) can offer a more holistic view of legal and physical situations, leading to better-informed decision-making processes.
This paper begins with an introduction and motivation on amalgamating BIM with LADM, followed by a discussion of related works on BIM/IFC and LADM in Section 2. Some recommendations of future works from researchers also included.Section 3 discusses on findings (benefits and challenges) concerning the integration of BIM and LADM, while Section 4 serves as the conclusion and discuss this paper's findings.

Previous works on BIM
Countries like the Netherlands, Australia, Turkey, Singapore, and Sweden have been working on integrating BIM principles into their land administration (LA) practices.Song et al., (2017) discussed the possibilities of incorporating 3D data from BIM.She claimed that BIM data is significant and valuable data source and can be utilized for detailed analysis and major project applications in a geographical information system (GIS) because BIM data rich in geometric and semantic information.Due to the growing interest in BIM, several researchers have underscored the use of BIM in the context of 3D LA in various nations, including Sweden (Sun et al., 2019), Australia (Atazadeh et al., 2017), Serbia (Sladić et al., 2018), Saudi Arabia (Alattas et al., 2021), Turkey (Gursoy et al., 2022), and the Netherlands (Broekhuizen et al., 2021).Atazadeh et al., (2017) proposed an extension to the BIM standard through integration into BIM model (e.g., complex building) to check on potential of leveraging BIM for high-rise buildings and modelling 3D ownership rights.He investigated how to store legal property in an IFC model and created a prototype model for a 3D Land Administration System (LAS) with input from the model.Figure 1 shows IFC models' physical data entities in a hierarchical data structure.In this figure, the most abstract entities are depicted in grey.Two main entities have been defined to model physical information in the IFC standard, namely IfcSpatialStructureElement and IfcBuildingElement.Meanwhile, Figure 2 shows the legal entities defined within IFC schema.The proposed entities are depicted in yellow.The IfcLegalPropertyObject entity represents all types of legal property objects such as 3D ownership spaces for units, common properties, and easements.
The prototype model demonstrates the potential benefits of BIM in high-rise LA.This extension aims to provide richer information about ownership and rights, supporting stakeholders that already using BIM.He recommended for more further development on IFC files to cater related information on high-rise building such as on topological aspect.(Atazadeh et al.,2017) Figure 2. Legal entities defined within IFC schema (Atazadeh et al.,2017)Then, Oldfield et al., (2018) investigated the possibilities of using BIM as input for 3D LAS.They proposed using IfcSpace as legal space and IfcZone for grouping spaces into legal zones.The integration utilized Information Delivery Manual (IDM) ISO 29481 Part 1 and 2. Part 1 coordinates processes such as building regulation conformance, rates assessment, topographic mapping, and asset management.Part 2 guidelines help in modelling an XML-based interaction framework for digital implementation.
Besides, Olfat et al., (2019) explores the potential of utilizing a BIM to enhance 3D digital building subdivision workflows.Current workflows often rely on fragmented and documentcentric approaches, leading to information silos.This research also contributes on extending the open BIM standard to incorporate subdivision lifecycle information, creating a 3D digital common data environment for sharing and exchanging information among stakeholders.The research aims to explore the feasibilities of constructing a BIM-enabled cadastral plan lodgment system for handling 3D digital data submission, storage, validation, visualization, examination, and map base updates.Figure 3 visualizes the integration of legal and physical objects as well as administrator information.This study primarily focuses on the Victorian jurisdiction; however, the approach can be adapted for other jurisdictions by modifying it to align with the specific workflow and data elements defined in specific regions.
Figure 3. Integrated BIM model comprising legal and physical objects, as well as administrative information for the case study building (Olfat et al.,2019) Meulmeeste, ( 2019) enriched an IFC model with legal data as a property set and transferred it into a conceptual 3D LAS.He investigated the requirements for IFC models to be defined as legal spaces within Dutch LAS.The investigation involves a thorough examination of both IFC data format and Dutch laws pertaining to apartment rights.Legal space, in the context of apartment rights, was conceptualized as the exclusive usage and access rights to a specific area within a building (see Figure 4).
According to Dutch law, an owner of an apartment right possesses the entire building but is restricted to accessing only the areas explicitly defined in the notarial deed.These areas are typically visualized through 2D floorplans, encompassing shared spaces like hallways and private spaces such as dwelling areas, storage units, or parking spaces.Next, Sun and Paulsson, (2019) proposed a framework (see Figure 5) for integrating BIM with LA, where both IFC and CityGML models were stored in a LADM database.The research connects IFC and CityGML models to generate a 3D cadastral model.The study acknowledges limitations, such as incomplete property descriptions, and recommends further research to test models, validate the framework, and develop collaborative workflows.Meanwhile, Barzegar et al., (2019) introduced a method for identifying various property boundaries (see Figure 6) in 3D using topological relationships and a BIM-based plugin.The approach is user-friendly, enabling individuals without cadastre expertise to understand and address boundary issues.It proves valuable for developers in multi-owned developments, aiding in informed decision-making and preventing potential disputes.An exploration for querying boundaries related to common properties and oblique walls, developing methods for constructing volumetric legal spaces, and implementing the algorithm in a web-based environment for broader stakeholder usability were recommended by the same author.2020) investigated the implementation of CityGML and IFC standards in the GeoBIM benchmark, focusing on the integration of 3D city models with BIM.It highlights flaws in georeferencing storage in IFC files and calls for collaboration to address the issue.Challenges in conversion tasks reveal the needs for explicit constraints, use-case-based considerations, and improved mapping of semantics and geometric features.The study underscores the lack of validation methods for IFC output models and suggests further exploration in this area.While limitations exist, the paper identifies key areas for development in software tools and standards, emphasizing the need for awareness and control of georeferencing methods, models between CityGML and IFC.Coordination between research, standardization efforts, and implementations is crucial for future progress in integrating geoinformation and 3D city models with BIM.
Furthermore, Alattas et al., (2021) developed an approach that integrates IFC and LADM to represent the legal spaces of properties in Saudi Arabia.The approach refines models with private, common, and exclusive common spaces.The hybrid approach integrates legal information into the 3D model while extending the LADM-based country profile with physical counterparts.The research addresses issues in the 3D IFC model related to spaces, floor slabs, and additional attributes, enhancing the definition of ownership rights.Recommendations for building subdivision authorities include using 3D 'as-built' models and providing clearer regulations for spaces and directions, together with extending the 3D country profile, improving administrative elements, and testing the hybrid approach in various country profiles and building types.
Moreover, Atazadeh, et al., (2021) used the IFC schema to model features and attributes in LADM.They plan to integrate real-world case studies by focusing on building developments with complex architectural designs.The authors also aim to refine the proposed approach, making it more feasible for integrating legal and physical dimensions of buildings in a 3D digital environment.Figure 7 shows different sections of the IFC standard, in which the legal and physical components are highlighted.In upcoming work, the creation process of legal boundaries referencing building elements can be automated within the integrated IFC file.An algorithm is recommended to empower users to choose which face (interior, median, or exterior) of a building element is utilized for delineating the legal boundary.Factor weights were determined through interviews, and land shares were obtained using a valuation method based on a comparative or relative approach.The study challenged the assumption that real values of condominium units facing difficulties to be accurately calculated in the initial phase of establishing condominium easement.The study also suggests establishing common standards within the Turkish property valuation system for broader acceptance of the proposed model.Broekhuize et al., (2021) evaluated BIM/IFC models in terms of IfcSpace existence, geometric validity, overlap, and the ability to georeferenced.There are several technical issues that still need to be addressed.This research utilized five BIM/IFC models as prototypes 3D LAS, incorporating LADM components.Notably, only IfcSpace entities were modelled as legal units due to legal constraints, and most of the BIM/IFC models utilized were based on the original design rather than the actual construction.et al., (2023).The integrated approach (BIM with LADM) enables stakeholders to efficiently share spatial and semantic information about complex building structures.Table 1 shows the other part of the preceding works on BIM.Some new classes in the IFC schema have been introduced to represent the legal spaces in complex buildings.Evaluates the applicability of Biljecki et al., (2016) framework in specifying BIMderived building models.The comparison involves two BIM shell extractors-IFC BuildingEnvExtractor and BIMShellagainst the Levels of Detail (LoDs) defined in the framework.
Several countries, including the Netherlands, Australia, Turkey, Singapore, and Sweden, have actively integrated BIM principles into their land administration practices.Researchers from various nations, such as Sweden, Australia, Serbia, Saudi Arabia, Turkey, and the Netherlands, have explored the potential of BIM in the context of 3D LA.These studies propose extensions, frameworks, and methods to enhance BIM's role in representing legal spaces, ownership rights, and property boundaries.They also addressed issues like interoperability, standards, and the integration of BIM with existing land administration models and showcasing the diverse applications of BIM/IFC across the globe.These efforts contribute to a growing body of knowledge aimed at leveraging BIM for efficient and accurate 3D representation of land and propertyrelated information (Kitsakis et al., 2022).

Potential IFC schema for amalgamating land administration practice
IFC schema holds significant potential for amalgamating land administration practices, providing a framework for representing complex relationships between physical and legal entities within the built environment.Its comprehensive structure allows for the integration of key elements, such as legal spaces, ownership rights, and property boundaries.
In the context of land administration, the IFC schema can serve as a common language for exchanging information between various stakeholders, including surveyors, land administrators, and urban planners.It offers a standardized way to represent 3D spatial information, enabling accurate modeling of cadastral data, property rights, and land use.The schema's flexibilities accommodate diverse requirements of different jurisdictions, making it adaptable to various legal frameworks and administrative practices.Some potential IFC schema that can be amalgamated into land administration practices can be seen in Figure 8.  (Guler et al., 2022) Figure 8 illustrates the potential IFC schema that can be adopted into LADM.IfcElement represents the physical elements or components of a building.IfcBuildingElement is generalized to IfcElement, which defines the properties and associations of physical building elements, such as walls, columns, beams, doors, windows, and other tangible components.IfcBuildingElementProxy serves as a subtype of IfcBuildingElement to delineate a non-predefined building's elements, for instance, lifts (elevators).IfcRelAssociatesDocuments is associated with IfcElement for linking between elements in buildings and external documentation relevant to those elements.This association will be beneficial in tracking and managing relevant documentation related to building elements, ensuring important information can be accessed and integrated.IfcActor is a class representing any person, organization, or role involved in a construction or building, where it serves as fundamental entity for capturing information about various stakeholders associated with a building.In this case, IfcActor is associated with IfcElement.IfcSpatialStructureElement is generalized to IfcElement to depict spatial elements, such as building stories, sections, components, spaces, and zones.IfcSpace is a potential class to be adopted to represent spaces with distinct characteristics and attributes, encompassing essential information, such as area, volume, height, and occupancy information.IfcSpace is associated with IfcRelSpaceBoundary and IfcBuildingProperty to define individual spaces and the spatial boundary between two spaces, such as apartments that are owned or leased.These IFC elements can be mapped into LADM according to its packages (Party, Administrative and Spatial Unit).
When mapping party package to IFC, LA_Party is represented by the IfcActor entity, which encompasses pertinent information about the involved parties.IfcActor includes details such as roles, contact information, and the legal representation of these parties.
In administrative package of LADM, LA_RRR class and its subclasses, encompassing LA_Right, LA_Restriction, LA_Responsibility, and LA_Mortgage, embody various types of rights, restrictions, responsibilities, and mortgages.In IFC, there is no direct equivalent entity for LA_RRR.Nevertheless, the attribute information of RRR can be documented in the legal file within IFC and linked to the IfcSpace attribute set.To represent legal documents, entities such as IfcPropertyTitle, IfcParentTitle, IfcPropertyDescription, IfcMortgage, and IfcCaveat can be utilized.Each IfcLegalPropertyObject can be linked to a legal file (IfcPropertyTitle), encapsulating ownership or other pertinent RRRs details.
LADM introduces the concepts of LA_SpatialUnit and LA_SpatialUnitGroup to depict the spatial units and their grouping within a condominium building.LA_LegalSpaceBuildingUnit represents the 3D legal space of LA_SpatialUnit.When translating to IFC, the IfcSpace entity is employed to correspond to LA_LegalSpaceBuildingUnit, symbolizing the individual spatial units within a condominium.A collection of spatial units (LA_SpatialUnit) is represented by LA_SpatialUnitGroup.In IFC, the IfcZone entity is utilized to match LA_SpatialUnitGroup, portraying the grouping or zones within the condominium.This implementation requires translating LADM concepts to their corresponding IFC entities and relationships.This mapping is crucial to seamlessly integrate ownership information from LADM into the 3D representation of the condominium or another complex building in IFC.

Land Administration Domain Model
Land Administration Domain Model (LADM) Edition I has been developed on 2012 (Lemmen, 2012) as a standard for land administration.This standard has been applied by various countries as a conceptual legal information model for 3D land administration as agreed by Lemmen et al., (2021); Kalogianni et al., (2021) and Sun et al., (2019).It provides a basic and standardized terminology for describing entities and their relationships, including RRRs of land properties which can be expanded to fit a nation's needs (Hjelmblom et al., 2019).Now, LADM has been extended become Edition II that covers basis land administration which are land tenure, land value, land use, and land development (Lemmen et al., 2019;Kalogianni et al., 2020) as illustrated in Figure 9.  (Enemark, 2005) Land tenure represents the assigning and security of land rights, legal surveys to establish parcel boundaries, sale or rental of property, and management of land rights and parcel boundaries.Land value represents land and property value assessment, the gathering of revenues through taxation, and the management of land valuation and taxation disputes.Land use comprises the control of land use by adopting planning policies and land use regulations at national, regional, and local levels.Land development comprises building new physical infrastructure, implementing construction planning, and changing land use through planning permission and granting permits (Enemark, 2005).LADM framework defines a clear and standardized way to represent legal and administrative aspects of land including properties' RRRs.By incorporating LADM concepts into BIM, the legal context of buildings and land parcels can be accurately captured.This ensures that, the representation of structures in BIM aligns with the legal framework defined by LADM.It ensures the cadastral boundaries and legal ownership rights are accurately reflected in the BIM model.Since LADM has been extended, it can give more information (e.g., RRRs, valuation, land use) to be integrated within BIM/IFC.This is particularly crucial for 3D land administration.Integration with BIM allows for the creation of comprehensive 3D cadastral models, where legal and administrative information is embedded within the BIM model, providing a more accurate representation of the legal context in a 3D environment.

Needs and Benefits
The integration of BIM with LADM has emerged as a promising field for 3D digital cadastre and efficient land administration, including 3D ownership (RRRs) management.The content of RRRs can be modeled based on the LADM standard national while BIM provides rich semantic information for land management activities.Combining BIM/IFC with LADM creates a correlation that enhances our understanding of the legal space in complex building Guler et al., (2022); Ying et al., (2021); Olfat et al., (2021).BIM is increasingly applied to 3D condominium ownership management, offering advantages like semantic relationships between legal spaces and together with ownerships.
Furthermore, architects and urban planners could leverage BIM data to create more informative and efficient designs, considering legal constraints and land administration requirements from LADM.The integration may improve interoperability between BIM and LADM allows for seamless data exchange, reducing data silos and enhancing communication between stakeholders.Government authorities able to make efficient decisions and develop policies that align with both physical and legal aspects of land and building development.Finally, the integration supports the delivery of enhanced public services related to land and property information, benefiting citizens, businesses, and government agencies.

Issues and Challenges
BIM models that meant to be for the registration of apartment rights should be in as-built form, otherwise incorrect cadastral information would be registered to the cadastral database.These models should have adequate information for the 3D registration of apartment rights.
Based on the previous works, some challenges (as stated) need to be considered when amalgamating BIM and LADM: • IFC models' inability to do georeferencing (Tauscher H. et al., 2023 Missing information due to the semantic integration of BIM and GIS (Zhu et al., 2019) It is quite challenging to integrate both LADM and BIM where LADM widely used as a conceptual legal (ownership) information model meanwhile BIM represents semantic building information with their own hierarchical data structure.
One of the ways to address the challenge as mentioned above has been proposed by Sun and Paulsson (2023) where Cadastral Level of Detail (CLOD) for representing both legal information, RRRs together with semantic information for 3D cadastral models could be utilized.Both legal and geometrical details are represented in five classifications: CLOD0, CLOD1, CLOD2, CLOD3 and CLOD4.The classes can be seen in Table 2. Since neither LADM nor BIM has an Application Domain Extension (ADE) mechanism, the integration between these two domains does pose challenges.Achieving interoperability without a standardized extension mechanism may lead to ad-hoc solutions, reducing the ability to seamlessly exchange information between the two systems.However, the integration may involve focusing on specific aspects where alignment is critical, such as incorporating key legal boundaries into BIM models.This selective approach helps to address certain use cases effectively.The limited integration provides practical and valuable solutions by focusing on specific use cases, key integration points, and collaborative efforts between stakeholders.

DISCUSSIONS & CONCLUSION
LADM and BIM are two different standards that serve different purposes where LADM is a standard for land administration and BIM focuses on modelling information related to build environments, for instances, buildings and infrastructures.
Mapping LADM concepts into IFC presents a significant benefit by enabling the linkage of legal information with building lifecycle data.The IFC standard serves as the foundation for managing building lifecycles in an open and interoperable manner, extending the value of legal information beyond property registration.This integration facilitates the determination of legal RRRs in property management.It also enhances communication and information exchange between land development stakeholders and land administration actors, such as land surveyors or registries.The strategy for extending LADM with IFC is particularly relevant in jurisdictions where building structures play a role in boundary delineation and essential to legal arrangements.By incorporating physical elements, this approach expands the scope of the LADM standard, accommodating diverse jurisdictional approaches to 3D property registration.It is clear that the integration leads to various advantages.
Besides the plus points, it also has limitations such as georeferencing, too many entities of BIM for LADM, the absence of IfcSpace for legal area, and no authoritative policy from national players on BIM-LADM integration.Thus, requires a thorough understanding for both standards in establishing effective interactions.
Based on the previous works, there are possibilities to integrate BIM/IFC into current land administration based on LADM.
Several countries have utilized BIM as part of their land administration practices.We believe that a review of this interesting domains -LADM and BIMwould lead to better insights and understanding of land administration.Further investigation on BIM-LADM can be conducted based on the recommendations that have been suggested by the researchers.

Figure 4 .
Figure 4. BIM enriched with legal space through a user defined property set visualised with Solibri Model Viewer.Figure (d) visualised with QGIS (Meulmeeste, 2019)

Figure 5 .
Figure5.The general framework for integrating cadastre with BIM and GIS(Sun and Paulsson, 2019)

Figure 7 .
Figure 7. Different sections of the IFC standard used for modelling legal and physical components (Atazadeh et al., 2021) Simsek and Uzun, (2021) proposed calculating property valuations based on BIMs in Turkey within the context of condominium ownership.This study utilized a 3D virtual BIM model to visualize topographic surfaces, analyze factors such as floor location and facade orientation for condominium units, and assess annexes.Energy analysis was performed using precise measurement data in Revit with the Insight 360 plug-in, considering factors like daylight and sun exposure.The calculation of nominal values and factor weights for real estate valuation requires expertise, often provided by estate surveyors.Factor weights were determined through interviews, and land shares were obtained using a valuation method based on a comparative or relative approach.The study challenged the assumption that real values of condominium units facing difficulties to be accurately calculated in the initial phase of establishing condominium easement.The study also suggests establishing common standards within the Turkish property valuation system for broader acceptance of the proposed model.

Table 1 .
Guler et al., 2022)ted to BIM (revised fromGuler et al., 2022) Establishes a correlation between the features of the LADM and entities present in the IFC schema to facilitate 3D land administration (Petronijevic et al., 2021) Extends IFC schema by new entities -IfcBuildingPropertyUnit for representing legal spaces in complex buildings (Barzegar et al., 2021) Suggests methodology for identifying the boundaries of legal spaces and storing them in a spatial database (Brooks, 2023) Provides a comprehensive overview