Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 Linking BIM and GIS Standard Ontologies with Linked Data Elio Hbeich1, 2, and Ana Roxin2 1 Information System and Applications Division, CSTB, Sophia Antipolis 06560, France 2 Université de Bourgogne Franche-Comté (UBFC) – LIB EA7534, Dijon 21000, France elio.hbeich@cstb.fr,ana-maria.roxin@ubfc.fr Abstract. Following the analysis of existing BIM and GIS standards, formats, differences in the interpretations of the underlying concepts have been identified. Still, in each of the two con- sidered domains several ontologies have been defined for these terms without seeking an align- ment among their definitions. With this scope in mind, this article presents several mappings expressed by means of explicit semantic links between GIS concepts (as present in the related ontologies for the ISO 191XX standard family) and BIM concepts (as represented in the IFC standard ISO 16739:2018). Such semantic mappings are defined in order to ensure a knowledge continuum between both domains, thus enabling seamless reasoning in application contexts spanning over them e.g. urban contexts. Keywords: BIM, GIS, Semantic Web Technologies, Ontologies, ISO stan- dards, Linked Data. 1 Introduction Building Information Modeling (BIM) and Geographical Information Systems (GIS) both address modelling of environments: traditionally GIS focus on natural en- vironment, whereas BIM targets built environments. Developed until now indepen- dently, both domains are addressed by different standards. Following " Building in- formation models — Information delivery manual — Part 1: Methodology and for- mat" (ISO 29481-1: 2016) [16], BIM is defined as a shared digital representation of physical and functional characteristics of any built object (including buildings, bridges, roads, etc.) which forms a reliable basis for decisions . According to "Geo- graphic information — Reference model — Part 1: Fundamentals" (ISO 19101- 1:2014) [10], GIS is an "information system dealing with information concerning phe- nomena associated with location relative to the Earth". Being initially conceived with different purposes, BIM and GIS differ in granularity: while BIM handles building in- formation with a high degree resolution, GIS handles data about natural environments along with man-made structures with a lower level of detail. Today these frontiers seem to vanish as decision-support systems for urban environments, public sector or even disaster management need to combine their features and advantages to improve quality of service. For example, to help new students arrive to their classes quickly and efficiently we need to connect outdoor navigation (supported by GIS) and build- Copyright © LDAC2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0). 146 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 ing (university) indoor navigation (supported by BIM). To guarantee information con- tinuity that can place buildings in urban context by adding its characters, analytic ca- pability and impact in urban environment we need to ensure seamless data interpreta- tion between both domains. Such data interpretation is ensured by transforming data into knowledge by means of Semantic Web approaches e.g. ontologies. Being an ex- plicit and formal conceptualization, an ontology has the benefit of ensuring computer- reasoning, thus interpreting data instances according to an ensemble of rules. Still, on- tologies on their own do not resolve the interoperability issue mentioned before e.g. the need for seamless interpretation across both domains. Following the Linked Data principles [1], vocabulary links must be defined among terms specified in different ontologies. While several ontologies have been defined in both domains, they have all been specified independently from each other and nor so many links and mappings have been defined among them. In the context of this article, we are solely aiming at standard ontologies in BIM and GIS domains, which are the ifcOWL ontology for IFC [22] and the ontologies defined by ISO/TC 211 for the ISO 19100 standard fam- ily (https://github.com/ISO-TC211/ontologies). Following a summary of technologies and standards encompassed by BIM and GIS domains, we present existing BIM and GIS ontologies (sections 2 and 3) along with previous mapping approaches among these ontologies (section 4). Section 5 presents the links we identified for these on- tologies: concepts and properties. Section 6 discusses those links and concludes the article. 2 BIM and existing standard ontologies 2.1 Building Information Modeling (BIM) BIM is the process of generating, storing, managing, exchanging, and sharing build- ing information [8] in an open format, namely IFC. BIM focuses on the creation of virtual 3D models that can be explored and modified by all the stakeholders involved in a construction project. At the level of the ISO, it is the Technical Committee ISO/ TC 59/SC 13 "Organization and Digitization of information about buildings and civil engineering works, including building information modelling (BIM)" that is in charge of developing BIM-related standards. Three main ISO standards exist for BIM: (1) In- formation Delivery Manual (IDM) (ISO 29481-1:2016) [16], (2) Model View Defini- tion (MVD) (“Building information models — Information delivery manual — Part 3: Model View Definition.”) (ISO 29481-3:2010) [17], and (3) Industry Foundation Classes (IFC) (“Industry Foundation Classes (IFC) for data sharing in the construction and facility management industries”) (ISO 16739:2018) [9]. A stakeholder specifies in natural language his requirements in the form of an IDM. This is translated into an MVD which represents a subset of the full IFC schema corresponding exactly to the requirements specified by the stakeholder. The IFC standard both comes with a data schema (defined in both EXPRESS and XML) and exchange file structures (clear text encoding of the exchange structure according to ISO 10303-21 and XML). Thus, BIM data is exchanged among stakeholders in the form of IFC files. For example, an archi- 147 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 tect creates an architectural model exports it in IFC version and shares it with an HVAC engineer. The HVAC engineer references the file and uses it for coordination or energy analysis. However, the HVAC engineer cannot modify the content provided by the architect (e.g. add a new wall): he/she needs to ask the architect to make these changes. For augmenting the efficiency of IFC-based exchanges and workflows, an MVD must be defined; e.g. definition of the specific IFC data schema subset pertain - ing to a given data exchange requirement for a specific software application. MVDs allow checking that the IFC data exchanged is conform to the exact requirements of the workflow considered. IFC data is structured into four different layers: (1) The re- source layer includes all individual schemas containing resource definitions, used in BIM project (e.g. IfcAddress, IfcReference); (2) The core layer contains the most general entity definitions as the kernel schema (e.g. IfcActor) and the core extension schemas IfcProcessExtension (e.g. IfcEvent), IfcProductExtension (e.g. IfcBuilding), IfcControlExtension (e.g. ifcPerformanceHistory); (3) The interoperability layer in- cludes definitions specific to a general product, process or resource as used across several disciplines (e.g. IfcDoor, IfcRamp, etc.); (4) The domain layer includes schemas containing entity definitions that are specializations of products, processes or resources specific to a certain domain (e.g. IfcHvacDomain, etc.). 2.2 Standard BIM Ontologies When considering standard BIM ontologies, only one ontology exists namely the ifcOWL ontology. The process generating this ontology is described in [22]. The ap- proach of [22] implements a conversion pattern (algorithm) provided in Java and C++ to convert the considered EXPRESS schema (simple, defined, list aggregation, array aggregation data types, etc.) into OWL (OWL class hierarchy, object properties, etc.). The generated ifcOWL ontology is in OWL2 DL, matches the original EXPRESS schema, and allows the conversion of IFC STEP files into equivalent RDF graphs. Different ifcOWL versions have been generated for each version of the IFC standard and are available online1. Several researches have tackled improving the standard if- cOWL ontology. [7] proposes an ifcOWL ontology where EXPRESS collections (e.g. LIST) are mapped as OWL properties, and IFC defined types are not directly con- verted to OWL classes. [7] proposes an IfcWoD ontology that has a lower expressiv- ity (ALUIF(D) instead of SHIQ(D) for ifcOWL). IfcWoD comes with two main advan- tages compared to the standard ifcOWL version: (1) EXPRESS collections are mapped as OWL properties instead of RDF or OWL Lists, and (2) IFC defined types aren't directly converted into classes. This allows having shorter and more efficient SPARQL queries. [4] transforms the Construction Operations Building Information Exchange (COBie) standard into the COBieOWL ontology (in OWL Lite with an ALCHIF(D) expressivity) and apply Linked Data principles for linking it to vocabular- ies such as FOAF. The COBieOWL ontology is also aligned to the ifcOWL ontology by transforming the COBie MVD into SWRL rules [6]. Federation among the Ifc- 1 https://github.com/buildingSMART/ifcOWL 148 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 WoD and the COBieOWL ontologies is implemented using the FOWLA framework [5]. 3 GIS and existing standard ontologies 3.1 Geographic Information Systems As mentioned in the Introduction, GIS refers to "information systems dealing with information concerning phenomena associated with location relative to the Earth" [10]. ISO/TC 211 "Geographical Information" is the ISO technical committee in charge of standardization in the field of digital geographic information. Its goal is to "establish a structured set of standards for information concerning objects or phenom- ena that are directly or indirectly associated with a location relative to the Earth" [18]. GIS represents the information system that allows handling such objects and phenom- ena [10]. ISO/TC 211 has defined the different standards forming the ISO 19100 stan- dard family. Conceptual modelling in the ISO 19100 series is based Model-driven Ar- chitectures (MDA). Four levels are considered: (1) Metamodel level contains “Geo- graphic information — Rules for application schema.” (ISO 19109:2015) [12], and “Geographic information — Conceptual schema language” (ISO19103:2015) [19], (2) Conceptual (Abstract) Schemas level contains “Geographic information — Spatial schema.” (ISO 19107:2003) [11], “Geographic information — Referencing by coordi- nates.” (ISO 19111:2007) [13], etc., (3) Conceptual (Applications) Schemas level contains “Geographic information — Data product specifications.” (ISO 19131:2007) [15], “Geographic information — Imagery sensor models for geopositioning” (ISO 19130:2010) [14], etc., and (4) Implementation schemas level contains the actual data that is defined according to the standards present at the previous level. 3.2 Standard GIS Ontologies ISO/TC 211 established a group for the maintenance of ontologies (GOM) respon- sible to create and publish ISO/TC 211 ontologies (https://github.com/ISO-TC211/ GOM). The table below lists the standards that have associated ontology representa- tions (as published on the TC211 website: https://def.isotc211.org/ontologies/). These ontologies are also published on the ISO/TC211 GitHub repository: https://github.- com/ISO-TC211/ontologies. Elements in bold in the table below are the standards concerned by the mappings defined in this paper. Table 1. ISO 19100 standard family ontology representation Metamodel level ISO Name Description standard ISO Reference The ISO reference model dealing with geographic information, de- 19101 model scribed from 4 viewpoints: semantic, syntactic, service, and proced- ural. One of the goals of this reference model is to "ensure interoper- ability" with other domains and to ease the integration of "integrate geographic information with other types of information and con- 149 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 versely". Conceptual It provides rules and guidelines for the use of a conceptual schema ISO schema lan- language within the context of geographic information. The concep- 19103 guage tual schema language used is the Unified Modeling Language (UML). The RulesForApplicationSchema imports UtilityClasses and Gener- alfeatureModel ontologies from ISO 19109:2015, along with the base Rules for ontology from ISO 19150-2:2012.The GeneralFeatureModel ontology ISO application imports UtilityClasses ontology from ISO 19109:2015, NameTypes 19109 schema ontology from ISO 19103:2015, MetadataEntitySetInformation onto- logy from ISO 19115:2003 along with the base ontology from ISO 19150-2:2012. Conceptual (Abstract) Schemas level ISO Name Description standard The SpatialSchema ontology imports Geometry and Topology ontolo- gies from ISO 19107:2003 along with the base ontology from ISO 19150-2:2012. The Topology ontology imports TopologicalComplex, TopologicalPrimitive, and TopologyRoot ontologies from ISO ISO Spatial 19107:2003 along with the base ontology from ISO 19150-2:2012. 19107 schema The Geometry ontology imports CoordinateGeometry, GeometricAg- gregates, GeometricComplex, GeometricPrimitive, GeometryRoot on- tologies from ISO 19107:2003 along with the base ontology from ISO 19150-2:2012 The TemporalSchema ontology imports TemporalObjects and Tem- ISO Temporal poralReferenceSystem ontologies from ISO 19108:2006 along with 19108 schema the base ontology from ISO 19150-2:2012. Methodology The MethodologyForFeatureCataloguing ontology imports FeatureC- ISO for feature ataloguing and FeatureCatalogueRegister ontologies from ISO 19110 cataloguing 19110:2016 along with the base ontology from ISO 19150-2:2012. The ReferencingByCoordinates ontology imports CommonClasses, Referencing ISO Coordinates, CoordinateReferenceSystems, CoordinateSystems, by coordi- 19111 Datums and CoordinateOperations ontologies from ISO 19111:2019 nates along with the base ontology from ISO 19150-2:2012. Spatial refer- It establishes a general model for spatial referencing using geographic ISO encing by ge- identifiers and defines the components of a spatial reference system. It 19112 ographic only covers the definition and recording of the referencing feature, identifier and does not consider the forms of the relationship. It defines the schema required for describing geographic information ISO and services. It provides information about the identification, the ex- Metadata 19115 tent, the quality, the spatial and temporal schema, spatial reference, and distribution of digital geographic data. Schema for The Coverages ontology imports CoverageCore, DiscreteCoverages, ISO coverage ge- ThiessenPolygon, QuadrilateralGrid, HexagonalGrid, TIN, and Seg- 19123 ometry and mentedCurve ontology from ISO 19123:2005 along with the base on- functions tology from ISO 19150-2:2012. Core profile It defines a core profile of the spatial schema detailed in ISO 19107 ISO of the spatial that specifies, following ISO 19106, a minimal set of geometric ele- 19137 schema ments necessary for the efficient creation of application schemata. Schema for It defines a method to describe the geometry of a feature that moves as ISO moving fea- a rigid body, such as feature that moves along a planned route, or mo- 19141 tures tion influenced by physical forces. ISO Schema of The standard provides ways to specify locations along linear elements 150 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 linear refer- such as transport network links or alignments. In essence, any object 19148 encing where a location can be referenced using one measure. It establishes principles for reporting data quality, and also defines a ISO Data quality set of data quality measures for use in evaluating and reporting data 19157 quality. Conceptual (Application) Schemas level ISO Name Description standard ISO The Terminology ontology imports TermRegister ontology from ISO Terminology 19104 19104 along with the base ontology from ISO 19150-2:2012. Imagery sensor mod- The ImagerySensorModelsForGeopositioningPart1_Fundamentals on- ISO els for tology imports SensorData ontology from ISO 19130-1:2018 along 19130 geoposition- with the base ontology from ISO 19150-2:2012. ing The DataProductSpecification ontology imports DPS, Specification- AdditionalInformation, SpecificationContentAndStructure, Specifica- tionDataCaputreInformation, SpecificationDataQualityRequirement, SpecificationDeliveryInformation, SpecificationIdentification, Spe- cificationMaintenanceInformation, SpecificationPortrayalInformation, SpecificationReferenceSystem, and SpecificationScopes ontolgies Data prod- ISO from ISO 19131:2007 along with the base ontology from ISO 19150- uct specifi- 19131 2:2012. The DPS ontotology imports SpecificationPortrayalInforma- cations tion, SpecificationScopes, SpecificationDataCaptureInformation, Spe- cificationDeliveryInformation, SpecificationReferenceSystem, Spe- cificationDataQualityRequirement, SpecificationIdentification, Spe- cificationMaintenanceInformation, SpecificationContentAndStructure, SpecificationAdditionalInformation ontolgies from ISO 19131:2007 along with the base ontology from ISO 19150-2:2012. Implementation Schemas level ISO Name Description standard It specifies the data structure and content of an interface that permits communication between position-providing device(s) and position-us- ISO Positioning ing device(s) to interpret position information and determine whether 19116 services the resulting position information meets the requirements of the inten- ded use. It provides an abstract model for developers of portrayal systems so ISO that they can implement a system with the flexibility to portray geo- Portrayal 19117 graphic data to a user community in a manner that makes sense to that community. It specifies the requirements for encoding rules, encoding services and ISO XML-based encoding, for the interchange of data that conform to the Encoding 19118 geographic information in the set of International Standards known as the "ISO 19100 series". The Services ontology imports ServiceMetadata, and ServiceModel ISO Services ontologies from ISO 19119:2005 along with the base ontology from 19119 ISO 19150-2:2012. Feature con- The FeatureConcepts ontology imports FeatureConceptDictionary, ISO cept dictio- and HierarchicalFeatureInformationRegister ontologies from ISO 19126 naries and 19126:2009 along with the base ontology from ISO 19150-2:2012. registers 151 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 Web map The MapServices ontology imports ExtentInformation, and Citation- ISO server inter- AndResponsiblePartyInformation ontologies from ISO 19115:2006 19128 face along with the base ontology from ISO 19150-2:2012. Imagery, gridded and ISO The IGCD ontology imports IGCDFramework ontology from ISO coverage 19129 19129:2009 along with the base ontology from ISO 19150-2:2012. data frame- work Location- It defines a reference model (e.g. enterprise, information, etc.) and a ISO based ser- conceptual framework that contains ontology, taxonomies, etc. for 19132 vices - Refer- location-based services (LBS), and describes the basic principles by ence model which LBS applications may interoperate. Location- It describes the data types, and operations associated with those types, based ser- for the implementation of tracking and navigation services. It is de- ISO vices - signed to specify web services that can be made available to wireless 19133 Tracking and devices through web-resident proxy applications, but is not restricted navigation to that environment. Location- based ser- It specifies the data types and their associated operations for the im- ISO vices - Multi- plementation of multimodal location-based services for routing and 19134 modal rout- navigation. ing and navi- gation It specifies procedures to be followed in establishing, maintaining and Procedures ISO publishing registers of unique, unambiguous and permanent identifi- for item reg- 19135 ers, and meanings that are assigned to items of geographic informa- istration tion. Geography It is developed within the Open Geospatial Consortium (OGC). GML ISO Markup Lan- is an XML schema for the description of application schemas as well 19136 guage as the transport and storage of geographic information. (GML) It defines a core profile of the spatial schema detailed Core profile ISO in ISO 19107 that specifies, following ISO 19106, a minimal set of of the spatial 19137 geometric elements necessary for the efficient creation of application schema schemata. Metadata - It provides the XML implementation schema for ISO 19115 specify- ISO XML schema ing the metadata record format and may be used to describe, validate, 19139 implementa- and exchange geospatial metadata prepared in XML tion It is divided into two parts Classification system structure, and Land ISO Cover Meta Language (LCML). The first part aims to develop future Classifica- 19144 classification systems that offer more reliable collection methods. The tion systems second part allows different land cover classification systems to be de- scribed based on the physiognomic aspects. Registry of representa- It specifies the process for establishing, maintaining and publishing ISO tions of geo- registers of representation of geographic point location in compliance 19145 graphic point with ISO 19135. location Cross-do- It establishes a methodology for cross-mapping between vocabularies ISO main vocabu- used by geospatial communities. Its purpose is to provide rules for en- 19146 laries suring consistency when implementing cross-mapping processes. 152 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 It defines rules and guidelines for the development of ontologies to ISO Ontology support geographic information over the Semantic Web. It defines the 19150 conversion of the UML standards into OWL. Ubiquitous This standard considers Ubiquitous Public Access to geographic in- ISO public access formation. It defines requirements in terms of standardization of sys- 19154 - Reference tems and services supporting it. model Following the cooperation with OGC's Sensor Web Enablement Observations ISO (SWE) activity), this standard comprises 2 parts as derived from pre- and measure- 19156 viously published OGC standards: Part 1 — Observation schema ments (OGC 07-022r1) and Part 2 – Sampling Features (OGC 07-002r3). Calibration and valida- It comprises 4 parts: Part 1 addresses optical sensors (published in ISO tion of re- 2014), Part 2 covers the domains of laser scanning e.g. LIDAR (pub- 19159 mote sensing lished in 2016), while Part 3 addresses SAR/InSAR (published in imagery sen- 2018) and SONAR will be considered by Part 4 (to be published). sors and data 5 parts are considered for this standard, but only Part 1 Conceptual ISO Addressing model has been published so far. It defines an address model along 19160 with definitions of concepts present in the model. 4 Related Work Previous sections (2 and 3) introduced existing BIM and ISO/TC 211 ontologies. However, there is no previous studies that tackled or created any links between them. This section lists several approaches addressing semantic links among BIM and GIS application. Semantic Web Technologies link BIM and GIS domains through uni/bi- directional integration [21], [22] or unification e.g. ontology covering both domains [3]. However, the presented approaches focus only on building models and treat spe- cific use cases. [2] worked on automatically generating CityGML LoD3 (City Geo- graphic Markup Language is an open standardized data model and exchange format that stores digital 3D models of cities and landscapes. The extendible international standard for spatial data exchange is issued by the OGC and the ISO/TC211) building models from IFC using Semantic Web Technology by mapping different entities and properties (e.g. IfcRoof equivalent to RoofSurface). [3] semantically integrated IFC and CityGML by conceiving the UBM ontology (Unified Building Model). For this authors defined semantic relationships between IFC and CityGML schemas through transformation rules (e.g. IfcBuilding is equivalent to UBMBuilding and UBMBuild- ing is equivalent to _AbstractBuilding). [20] introduces BIM to GIS (B2G) mapping by applying perspective definition (B2G PD), element mapping (B2G EM) and LoD mapping (B2G LM) mechanisms. Where B2G PD concerns data extracting depending on the use case, B2G EM defines the object mapping mechanism in terms of BIM to GIS transformation of model elements. B2G LM concerns LoD definition and map- ping from BIM to GIS model. [21] integrates BIM and GIS by applying the following steps: (1) ontology construction, (2) semantic integration through Graph Matching for Ontologies (GMO), and finally (3) query execution. In addition, IFC ontology is linked to other building ontologies, for example [24] presents mapping results be- 153 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 tween BOT (Building Topology Ontology) and other building ontologies such as IFC (e.g. bot:Site owl:equivalentClass ifc:IfcSite), SAREF4BLDG (SAREF Ontology for Building) (e.g. bot:Building owl:equivalentClass saref4bldg:Building), and BRICK (e.g. bot:Building owl:equivalentClass brick:Building). Following our analysis, we noticed the following limitations in existing approaches: (1) the mappings defined are mainly among IFC and a GIS application schema (CityGML, IndoorGML, etc.) and do not address GIS standard ontologies; (2) unification or integration approaches only link two ontologies (e.g. CityGML and IFC) and cannot be applied to link all existing BIM and GIS ontologies; (3) most mapping concentrate only on IfcProductExtension and the IFC concepts in the interoperability layer. Thus in the next section we'll exam- ine and define several semantic links among concepts from ifcOWL and standard GIS ontologies. Our mapping concerns IFC4.1 (IFC4_ADD1 Ontology) which is the lasted IFC ontology published by buildingSMART and ISO/TC 211 ontologies [25- 29] (ISO 19109:2015, ISO 19107:2003, ISO 19111:2019, ISO 19130:2018, ISO 19131:2017 ) published by GOM. Figure 1: Previous mapping between BIM and GIS Ontologies 5 Ontology Mapping/ Alignment As stated before we are aiming to map BIM/GIS through the definition of semantic links among standard ontologies namely those defined by ISO/TC 211 and IfcOWL 4.1. As described in [23], this contribution is part of a wider approach based on a two- axis federation e.g. vertical and horizontal federation. In our vision, horizontal federa- tion focuses on creating semantic links between concepts and properties among both domains, while vertical federation specifies different abstractions of the same scope or context. Due to the limited number of pages, in this article we are only presenting mappings among a reduced number of ontologies from all those defined by ISO/ TC211. The links provided in the following paragraphs pertain to horizontal federa- tion and are intended to: (1) link the GIS metamodel e.g. the General Feature Model (GFM) or ISO 19109:2015 and IFC concepts present in its core layer. (2) link GIS ab- stract conceptual schemas (e.g. ISO 19107:2003, ISO 19111:2007) and IFC concepts 154 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 contained in the resource definition layer. (3) link GIS application schemas (e.g. ISO 19130:2010, ISO 19131:2007) and IFC concepts from the layers of domain specific and shared elements (ISO 16739-1:2018). In addition, note that the below standards correspond to the following name spaces:  ISO19107 = "http://def.isotc211.org/iso19107/2003/SpatialSchema#”  ISO19109 ="http://def.isotc211.org/iso19109/2015/ RulesForApplicationSchema #”  ISO 19111= "http://def.isotc211.org/iso19111/2019/CoordinateReferenceSystems#"  ISO 19130= "http://def.isotc211.org/iso19130/2018/SensorData#"  ISO 19131= " http://def.isotc211.org/iso19131/2007/DPS#"  IFC4.1 = "http://ifcowl.openbimstandards.org/IFC4_ADD1#" 5.1 Alignment between abstract schema and resource layer In this section we are mapping GIS abstraction schema (ISO 19111:2007, ISO 19107:2003) and IFC resource definition layer. Table 2. IFC4.1 and ISO 19111:2007 [13] concepts and properties IFC resource ISO Description Description layer 19111 It is the non-repeating se- quence of coordinate system Coordi- axes that span a given coordi- IfcCoordi- It is a definition of a coordi- nateSys- nate space. A CS is derived nateRefer- nate reference system using tem from a set of mathematical enceSystem qualified identifiers only. (CS) rules for specifying how coor- dinates in each space are to be assigned to points. It is a coordinate reference It is a derived coordinate ref- system of the map to which erence system which has a ge- the map translation of the lo- Project- odetic coordinate reference IfcProjectCRS cal engineering coordinate edCRS system as its base CRS and is system of the construction or converted using a map projec- facility engineering project re- tion. lates. Provides location and orienta- tions to place items in a three- IfcAxis2Place- dimensional space. The at- Coordi- Defines coordinate system ment tribute Axis defines the Z di- nateSys axis (axisAbbre, axeDirection, 3D rection, RefDirection the X di- temAxis axe UnitID). rection, the Y direction is de- rived. Table 3. Mapping IFC4_ADD1 and ISO 19111:2019 [27] IFC4_ADD1.owl Relation ISO 19111.owl IFC4.1:IfcProjectedCRS owl:equivalentClass ISO19111:ProjectedCRS IFC4.1:IfcCoordinateRef- owl:equivalentClass ISO19111:CoordinateSystem erenceSystem 155 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 IFC4.1:refDirection_If- ISO1911:CoordinateSystemAx- owl:equivalentProperty cAxis2Placement3D is.axisDirection Table 4. IFC4.1 and ISO 19107:2003 [11] concepts and properties IFC ISO resource Description Description 19107 layer Directed topological object that represents Defines 2 vertices being TP_ IfcEdge an association between an edge and one of connected topologically. Edge its orientations It is the super type of all boundary conditions that can be applied to structural The boundary operation for GM_Complex IfcBound- connection definitions, ei- GM_ objects shall return a GM_Com- ary ther directly for the con- Boun plexBoundary, which is a collection of Condition nection (e.g. the joint) or dary primitives and a GM_Complex of dimen- for the relation between a sion 1 less than the original object structural member and the connection Defines 2 vertices being connected topologically GM_Curve represent sections of curvilin- IfcEdge GM_ including the geometric ear geometry, and therefore share a num- Curve Curve representation of the con- ber of operation signatures. nection Table 5. Mapping IFC4_ADD1 and ISO 19107:2003 [26] IFC4_ADD1.owl Relation ISO 19107.owl IFC4.1:EdgeCurve owl:equivalentClass ISO19107:GM_Curve IFC4.1:Edge owl:equivalentClass ISO19107:TP_Edge IFC4.1:IfcBoundaryCondition owl:equivalentClass ISO19107:GM_Boundary 5.2 Alignment between application schema and shared element layer In this section we are mapping GIS application schema (ISO 19131:2007, ISO 19130:2010) and IFC shared element layer. Table 6. IFC4.1 and ISO 19130:2010 [14] concepts and properties IFC shared ele- ment layer Description ISO 19130 Description schemas It is the time It is the value of the duration of periods. value of the IfcTimeMeasure Measured in seconds (s) or days (d) or dateTime taken measure- other units of time. ment IfcDimension- It defines the dimensionality of the co- num- Number of di- Count ordinate space. It is restricted to have berofDi- mension the dimensionality of either 1, 2, or 3 mensions 156 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 for the purpose of this specification Table 7. Mapping IFC4_ADD1 and ISO 19130:2018 [28] IFC4_ADD1.owl Relation ISO 19130.owl ISO19130: SD_Dynamics. IFC4.1: IfcTimeMeasure owl:equivalentProperty dateTime ISO19130:SD_DetectorArray. IFC4.1: IfcDimensionCount owl:equivalentProperty numberOfDimensions Table 8. IFC4.1 and ISO 19131:2007 [15] concepts and properties IFC shared Description ISO Description element layer 19131 schemas IfcApplication It holds the information DPS_ It defines the conceptual about an IFC compliant ApplicationSchemas schema for data required application developed by by one or more applica- an application developer. tions IfcExtended- It is an abstract super Ex_Extent It presents the descrip- Properties type of all extensible tion of spatial and tem- property collections that poral extent covered by are applicable to certain data product characterized entities. Table 9. Mapping IFC4_ADD1 and ISO 19131:2007 [29] IFC4_ADD1.owl Relation ISO 19131.owl ISO19131: DPS_Application- IFC4.1:IfcApplication owl:equivalentClass Schemas IFC4.1:IfcExtendedProperties owl:equivalentClass ISO19131:Ex_Extent 5.3 Alignment between Metamodel and core layer In this section we are mapping abstract GIS schema (ISO 19109:2015) and IFC core layer. Table 10. IFC4.1 and ISO 19109:2015 [12] concepts and properties IFC core Description ISO Description layer 19109 IfcRoot IfcRoot is the most abstract and root Any It represents the set of all class for all entity definitions that roots Feature classes which are feature in the kernel or in subsequent layers of types the IFC specification. It is therefore the common super type of all IFC entities, beside those defined in an IFC resource schema IfcProduct Further specializes the concepts of a At- It recognizes all kinds of at- Extension (physical) product, i.e. a component tribute tributes: temporal, spatial likely to have a shape and a placement Type geometry, spatial topology, within the project context data quality, generic meta- data, and location. 157 Proceedings of the 8th Linked Data in Architecture and Construction Workshop - LDAC2020 Table 11. Mapping IFC4_ADD1 and ISO 19109:2015 [25] IFC4_ADD1.owl Relation ISO 19109.owl IFC4.1:IfcRoot owl:equivalentClass ISO19109:AnyFeature IFC4.1:IfcProductExtension owl:equivalentClass ISO19109:AttributeType 6 Conclusion and Future Work The above mappings rely on concepts' and properties' definitions to instantiate equivalent relationships. However, those relations are not enough to achieve full se- mantic interoperability. In order to push our contribution further, we need to confront conceptual and semiotic heterogeneities which address differences in modelling, cov- erage and granularity representation between ontologies. We also need to implement structural ontology matching techniques that could enable a more robust mapping be- tween BIM and GIS domains. Mapping BIM and GIS conceptual schema via ontolo- gies will enable us to create data continuity between both domains, plug BIM model into any GIS application (e.g. CityGML, IndoorGML, LandInfra, etc.). 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