=Paper= {{Paper |id=Vol-1323/paper27 |storemode=property |title=A Data Model for Integrating GIS and BIM for Assessment and 3D Visualisation of Flood Damage to Building |pdfUrl=https://ceur-ws.org/Vol-1323/paper27.pdf |volume=Vol-1323 }} ==A Data Model for Integrating GIS and BIM for Assessment and 3D Visualisation of Flood Damage to Building== https://ceur-ws.org/Vol-1323/paper27.pdf
               A Data Model for Integrating GIS and BIM for
        Assessment and 3D Visualisation of Flood Damage to Building


      Sam Amirebrahimi                 Abbas Rajabifard                      Priyan Mendis                       Tuan Ngo
     amis@unimelb.edu.au            abbas.r@unimelb.edu.au pmendis@unimelb.edu.au                          dtngo@unimelb.edu.au

            Department of Infrastructure Engineering, The University of Melbourne, VIC 3010


                                                              Abstract

                            Flood Damage Assessment (FDA) is a key component in
                            modern risk management frameworks providing an
                            effective basis for decision making and the treatment of the
                            risks. Current FDA methods do not consider the
                            distinctiveness of buildings in analysis and therefore,
                            cannot analyse them on a case-by-case basis, which is
                            necessary for a variety of applications like engineering and
                            design evaluation. This is mainly due to the limited input
                            data used in these methods. The information required for
                            such micro-level FDA analysis includes on one hand,
                            complete building information (well-represented in BIM)
                            and on the other hand, flood information that is commonly
                            managed by GIS. While the independent use of BIM and
                            GIS cannot satisfy all the information requirements for
                            detailed FDA, their integration can potentially be used for
                            this purpose. However, existing integration methods are
                            application-specific and their adoption for FDA is
                            challenging. This paper presents a method for BIM-GIS
                            integration to support the requirements of a detailed
                            assessment and 3D visualisation of flood damage to
                            buildings. The data modelling cycle was used to design a
                            new data model as a profile of GML for this purpose. The
                            model was evaluated using a case study and found
                            effective to satisfy the required criteria for micro-level
                            FDA.

   1 Introduction
       It has been recognised in the past decade that a management of flood risks which focuses solely on the hazard is
   not effective (Birkmann et al., 2013). Therefore, risk-based flood management commonly employs Flood Damage
   Assessment (FDA) to evaluate the potential consequences of flood in the identification of risks and decisions for
   their treatment (Thieken et al., 2005).
       Efforts in the field of FDA have resulted in development of a variety of FDA methods to serve different
   applications at different spatial scales (i.e. Macro, Meso and Micro) such as risk mapping, vulnerability assessment
   or financial appraisal of damage. Within this context, a strong emphasis is made on buildings due to their significant
   economic importance (Messner et al., 2007). The internationally accepted standard method for FDA is the use of
   "damage curves" (Merz et al., 2010). Damage in this method is calculated using generalisation of buildings into
   classes (based on a few of their general characteristics like construction type or age) and applying a predefined
   curve (or function) to relate the damage level commonly to a single flood parameter, the inundation depth. While

   Copyright © by the paper’s authors. Copying permitted only for private and academic purposes.
   In: B. Veenendaal and A. Kealy (Eds.): Research@Locate'15, Brisbane, Australia, 10-12 March 2015, published at http://ceur-ws.org
Research@Locate '15                                                78
   the effectiveness of the existing FDA approaches is confirmed for large scale applications investigating a large
   population of buildings (Messner et al., 2007), they are however found unfit for micro level applications (e.g.
   building design evaluation against flood) where a case-by-case assessment of the flood impacts on individual
   buildings is required (Pistrika and Jonkman, 2010). This is mainly because of the inability of these methods for
   capturing and use of a complete representation of the building in the assessment, due to their limited input data
   (Merz et al., 2010). In this way, uniqueness and distinct behaviour of building against the flood is not included in
   the analysis of damage. In addition, the outputs provided by these methods are limited to a single number for the
   overall building damage cost or only an indication of whether the building collapses or not for certain level of water
   and velocity. Other than these, no further information about the details and the location of damage at the building
   level is provisioned. Such details are important to reveal the sources of risk for a building for their treatment.
      An effective case-by-case analysis of damage to a building at micro level requires the use of two sets of
   information: the flood parameters (e.g. depth and velocity) causing damage to the building components; and the
   building components that resist against the flood impacts and are unique to each building (Pistrika and Jonkman,
   2010). Geographic Information Systems (GIS) are the key information management tools for the first set with a
   long history of use in this area. The major strength of GIS is on representation of outdoor and large scale features.
   However, even with the considerations of the recent efforts for 3D modelling of the details of the buildings in 3D
   city models (e.g. CityGML), the geospatial domain is still found inadequate for a complete representation of the
   semantic and geometric aspects of the building and therefore limited for the second set (Zhang et al., 2009). In
   contrast to GIS, Building Information Models (BIM) from the construction industry provides a comprehensive
   digital repository of building information. While the strength of BIM lies in the complete representation of every
   aspect of a building (e.g. geometry, materials and connections), it is restricted to small scale at a building level and
   currently cannot store geographically extended features like flood.
      The independent adoption of BIM or GIS for a micro level FDA would be inadequate to support the information
   requirements for this application. However, their combination provides the potential to accommodate these
   requirements under one umbrella to serve the analysis and presentation of the damage to the building (Isikdag and
   Zlatanova, 2009a). For the overall benefit of integrating BIM with GIS for different applications, numerous efforts
   were made towards its realisation. These works however, are limited to either (a) addressing the underlying
   technical integration challenges by one or two-directional geometry or semantic conversion between the two at
   building level or (b) serving a specific use case (e.g. indoor-outdoor utility management or emergency response)
   with focus of the integration on the minimum requirements to satisfy the needs of that application. The specific
   focus of these works limits their adoptability and use for FDA and therefore there is a need for a solution for
   integration of BIM with GIS for this purpose.
      In this paper, a method for combining the BIM and GIS at the data level is proposed to serve the information
   needs for a micro level assessment and 3D visualisation of potential building damage from floods. It is hypothesised
   that the use of this method can facilitate an information system to harness the combined strength of the BIM and 3D
   GIS, allowing for a case-by-case analysis of the building damage by the implementation of certain analysis types at
   a level of detail that the existing FDA methods are not sensitive towards. The outputs produced by such analyses
   can facilitate decision making by a range of stakeholders such as engineering and design firms, councils and
   insurance companies for improving the resilience of the community towards floods and their adverse impacts.
      In the remainder of this paper, first, the research background as well as an overview of the related work for the
   integration of BIM with GIS is provided. Next, the design of the proposed integration method and its details are
   presented. Further, a demonstration of the integration using a case study is illustrated and the results are discussed.
   Finally, the paper is concluded and the future research directions are proposed.


   2 Background and Related Work
   2.1 Building Information Model
       BIM is a rich and intelligent digital repository of building information and uses an Object Oriented (OO)
   approach to describe the characteristics (semantics and geometry) and behaviour of each building element as well as
   its relationships with others (Eastman et al., 2011). BIM uses Industry Foundation Classes (IFC) as its open
   standard to establish interoperability in the construction industry. Within the IFC framework, building, its
   components as well as other relevant construction industry data are described within a single information model
   enabling the management of such information throughout the lifecycle of a building/facility. Although BIM has a
   variety of applications and has been previously used for damage assessment for other hazards like fire and
   earthquake (e.g. Christodoulou et al., 2010), yet, it has not been considered for the case of FDA.

   2.2 Geographic Information System (GIS)
      GIS, on the other hand, is a platform for managing and presenting spatially referenced information. Within this
   domain, the exchange of geospatial data and the interoperability between systems are established using the
   Geographic Markup Language (GML). GML is an Open Geospatial Consortium (OGC) standard data model for
   defining the data types and constructs for describing the geographic features. With a more specific focus, the



Research@Locate '15                                          79
   heterogeneous geospatial information about urban data (e.g. buildings, transport, vegetation and water bodies) at
   different levels of details is integrated within the framework of the 3D virtual city models such as CityGML
   (Dollner et al., 2006). CityGML is the most comprehensive urban information model within the geospatial domain
   to digitally represent a city in 3D. The building information in CityGML (and other existing GIS formats) however,
   is not as complete and mature as BIM and for this reason, multiple extensions (e.g. utility network in Hijazi et al.,
   2010) have been created separately over the past years to improve the model. CityGML and some of its extensions
   have considered flood depth (as a water body), however, they were solely used for 3D visualisation of the flood
   (Schulte and Coors, 2009) and did not include its other parameters (e.g. velocity) and temporal dynamics. These, in
   addition to the other limitations of CityGML to represent the building details, prevent its effective use for serving
   the requirements of the micro-level FDA.

   2.3 BIM-GIS Integration
      GIS and BIM originate from different domains and were developed for the specific needs of that field. Their
   integration creates a seamless and scale-independent view of the world across both domains. It can benefit a variety
   of applications that meeting their requirements would not be possible by independent use of BIM or GIS (Karimi
   and Akinci, 2010). This integration however is not simple due to the differences between the two. Such
   dissimilarities are discussed in terms of spatial scale, level of granularity, geometry representation methods, storage
   and access methods as well as semantic mismatches between them (Isikdag and Zlatanova, 2009b; Karimi and
   Akinci, 2010; El-Mekawy and Ostman, 2010).
      Various attempts have been made for integrating BIM with GIS that can generally be classified into three
   groups: at application, process, and data levels.
      At the application level, the integration methods use reconfiguring or rebuilding (Karimi and Akinci, 2010)
   where an existing GIS or BIM tool is either modified by software patches or is rebuilt from scratch to include the
   functions of the other. This method is generally costly and inflexible. On the other hand, process level integration
   methods like OWS-4 project by OGC (2007) use Service Oriented Architecture (SOA) to allow the participation of
   BIM and GIS systems in those tasks that require the capabilities of both while they simultaneously remain live and
   distinct. This method provides more flexibility than the first group. However, in this method, the challenges of
   integration are still to be resolved at the underlying data level to provide interoperability between these systems.
      There are a variety of methods developed to integrate BIM with GIS at the data level. Linking methods such as
   ESRI ArcSDE facilitates data transfer between BIM and GIS software by an Application Programming Interface
   (API) at either side. Translation/Conversion methods such as FME (Safe, 2013) and the work by Nagel et al.
   (2009), on the other hand, were introduced to directly convert between GIS and BIM formats. This method
   commonly translates the data between IFC and CityGML. Loss of semantics, limitations in geometric conversion
   and sole focus on the major building elements and neglecting the other aspects (e.g. utilities or connections) are
   some of the concerns associated with these methods. To resolve the geometry transformation problem, a number of
   research (e.g. Li et al., 2006; Wu et al., 2010) was conducted which only partially addresses the overall integration.
      In the more comprehensive and flexible integration methods, either a new data model as a "meta model" is
   developed to mediate between BIM and geospatial information at higher level; or a data model at GIS or BIM side
   (e.g. CityGML or IFC) is extended to incorporate the data from the other. The GeoBIM and utility network
   extensions by Van Berlo and Laat (2010) and Hijazi et al. (2010) are examples for CityGML. On the other hand,
   IFC-for-GIS project (IAI, 2005) intended to extend the IFC model to include information from geospatial world. A
   prominent example of meta models is the "Unified Building Model" (El-Mekawy et al., 2011) that the focus of the
   integration was to develop an intermediate data model for building for emergency evacuation purposes. In general,
   these models are application-focused and the integration is made for a particular use case with specific
   requirements. Therefore, the included concepts and relationships within these models may not suit other
   applications (with different functional requirements).
      In this paper, an integration method for integration of BIM and GIS for micro-level assessment of flood damage
   on building is presented. It supplies the resistance parameters of the building at high level of details, flood
   information as well as the other geographically extended features (e.g. elevation) in one unified data model to use
   for assessment and 3D visualisation of the flood damage to building.


   3 BIM-GIS Integration for FDA on building
       The integration of BIM and GIS in this work is proposed at the data layer and implemented on the GIS side for
   utilisation of its spatial analysis tools for FDA calculations. The GML standard does not explicitly define the
   semantics of the geographic features (e.g. buildings or roads), and as discussed previously, there are limitations in
   representation of building and its components in the CityGML. For this reason, a new data model as a profile of
   GML is proposed to integrate the BIM information alongside the spatiotemporal dynamics of the flood information
   for assessing and visualisation of the damage on the building.




Research@Locate '15                                          80
   3.1 Methodology
       The proposed data model in this paper was developed based on the "data modelling cycle" (Teorey et al., 2011).
   This methodology includes five steps for design and implementation of a data model. It commonly starts with the
   mapping of the real world concepts and their relationships to a conceptual model. The concepts and relationships in
   the model are identified for a particular or a number of use cases by employing a variety of data requirement
   gathering methods like survey, interview, review of relevant previous publications, etc. The conceptual data model
   is further translated to the logical data model defining the structure of the database. The last step in the process
   involves the development of a physical data model and its implementation (Elmasri and Navathe, 2011).
       Next, the details of the above process for designing the proposed data model is explained, the outputs are
   presented and its benefits for use for a micro-level FDA are discussed.

   3.2 Use case definition
       Use cases are informal scenarios describing the expected behaviour of a system as a response to the needs of the
   stakeholder(s). Use cases are the basis of the extraction of the required functionalities and the data needs for system
   design.
       In this study, the defined use case is related to the assessment and visualisation of the potential damage to a
   building from a riverine flood. It requires (i) the assessment of the building safety (structural stability) by assessing
   the damage to structural and load bearing components, (ii) the estimation of the total cost of repair/replacement of
   the damaged components (excluding its content), and (iii) the visualisation of the location and mode of damage at
   component level. This use case was detailed by investigating the land development process, a review of previous
   publications and liaising with engineering and design firms, councils as well as referral authorities (e.g. Melbourne
   Water) as potential users of the system outputs. The behaviour of buildings of different types may vary in flood
   situations and the processes for damage analysis on them may be different from one to another. In this research, the
   scope was limited to only one type which represents the most common Australian residential construction type: a
   single-storey slab-on-ground brick veneer house (Geoscience Australia, 2014).

   3.3 Requirement analysis
      Based on the definition of the use cases in Section 3.2, the vulnerable components of the selected house type
   were identified. This process involved a systematic and extensive review of the literature (e.g. HNFMSC, 2006;
   CLG, 2007), discussions with engineers and councils, as well as the resources and previous research on the
   vulnerability of houses in Australia provided by the Geoscience Australia. Our findings indicated that for the
   construction type in focus, the damage and the incurred costs are mainly from the impacts of floodwater contact and
   forces on the floor covering, walls (including cladding, framing, insulation and lining), skirting boards and
   cornices, ceiling and its insulation, roof, windows, internal and external doors, eaves lining and the interior and
   exterior utilities (e.g. electrical) depending on their location and materials.
      Following the identification of susceptible components, further investigation was undertaken to identify and
   document (a) the modes of damage for each component from floodwater impacts, (b) engineering methods for their
   modelling and (c) the information inputs for these calculations. For the first two steps, Australian design and
   construction standards (e.g. AS3700 - masonry building design) and relevant documents for improving the house
   resilience to flood (e.g. HNFMSC, 2006; CLG, 2007) were used. Due to the limited space in here, the outputs of
   these two are not presented in here. Due to the diversity and large number of the extracted data requirements in step
   (c), only a subset of them is presented in Table 1 according to their importance. Other concepts like details of utility
   objects and types of different elements like coverings are omitted in this table.

                                   Table 1: Example of the Extracted Data Requirement
   Concepts       Details
   Spatial        Defining the spatial container for objects. It can have a corresponding element (e.g. building storey
   Structures     or a space in the building) that acts as the container object.
   Terrain        Representing the elevation of the area. It is required to be in multiple levels of details. Terrain can be
                  either point-based or surface-based.
   Flood          The flood parameters using multiple representations: (a) Spatio-temporal point distribution of depth
                  and velocity vectors (for use in damage calculation); (b) Surface representation of flood (e.g. water
                  level surface).
   Buildings      The footprint, address, height and the area.
   Building       Including storeys, walls, stairs, floors, foundation, beams, columns, roof, structural connections (e.g.
   components     wall ties), framing members, floorings, ceiling, soffit, skirtings and mouldings, doors, windows and
                  cladding vents (e.g. airbricks).
   Utilities      For example, electrical objects like switches, meter boxes and outlets.
   Materials      Construction materials of the building elements (single material or multiple)
   Cost info.     Including cost of repair/replacement of building and utility components; and the building value.




Research@Locate '15                                           81
   3.4 Data model design
      According to the identified requirements, the conceptual data model illustrating the required concepts and their
   relationships was designed. Throughout the design process, a continuous investigation was undertaken to identify
   how these concepts are modelled in BIM (IFC) or GIS formats (GML and CityGML). This mapping was used to
   refine the design to improve interoperability and information translation between IFC or CityGML and the
   proposed model. The data model consists of seven packages inheriting its high level feature definitions from the
   GML. These packages are namely: the Core (CoreUrbanFlood), Terrain, Flood, Building, Utility, Valuation and
   MaterialDomain. In this paper, the UML class diagram was employed for developing and presentation of the data
   model. Due to the complexity of the model and limitations in space here, the attributes are not illustrated in the class
   diagrams. In addition, each package and their respective classes are colour-themed for the ease of read.
      The "CoreUrbanFlood" package (see Figure 1) includes the necessary high-level objects for a micro-level FDA
   on a building. "UrbanFloodModel" concept is the highest level entity in the model defining an urban flooding
   scenario. It is a collection of defined materials, costs, spatial structures (explained in Section 3.3) and urban
   elements (_UrbanObject) representing the urban environment in a flooding situation. Urban objects can be the
   parcels (site), buildings, individual utility elements (_UtilityObject) or their aggregation as a system
   (UtilitySystem), flood representation (_FloodObject), and a simple or complex elevation model (_TerrainObject).
   Other urban objects like city furniture, roads, etc were beyond the scope of requirements in this research as the
   focus is only on damage assessment on buildings.




                                        Figure 1: UML Model of the Core Package

      The proposed data model adopts a subset of the "Digital Terrain Model" thematic model in CityGML 2.0 for its
   Terrain package (see Figure 2). An elevation object in here can be stored by an independent subtype of the abstract
   concept "_TerrainObject". It can be either a surface-based object (e.g. TIN) represented by "TinTerrain" or in a
   multi-point form using "MassPointTerrain". On the other hand, a single Terrain can be represented by an
   aggregation of a number of _TerrainObjects in different representation forms and levels of details within the
   "Terrain" object. Each _TerrainObject has a validity extent - represented by a polygon, to define its effective scope.




                                       Figure 2: UML Model of the Terrain Package




Research@Locate '15                                          82
       The Flood package, illustrated in Figure 3, consists of the required classes to represent the flood information.
   Any flood in the model (_FloodObject) is described by its metadata (FloodMetadata) that provides information
   about its exceedance probability, flood duration, number of time steps, duration of each step and the units of
   measurement for depth and velocity. As a subtype of the abstract _FloodObject, the "FloodBody" represents the
   flood in urban area in either point coverage or GML surface forms. In GML, a coverage class (e.g.
   multiPointCoverage) uses the relationship between RangeSet and DomainSet to link the geometry with its attributes
   (see GML 3.2.1 specification for details). The flood extension for CityGML by Schulte and Coors (2009) was
   adopted in this work and extended via definition of an array of "FloodTimeSeriesElement" classes (containing
   water depth and velocity components of the flood for a particular time step) to accommodate the temporal aspects
   of the flood in addition to its spatial components.
       Surface representation of the flood was specifically considered for its 3D visualisation. It can either be presented
   by a single MultiSurface object using "RepresentedBySurface" relation for the maximum depths; or using the
   aggregation hierarchy of timeSeriesSurfaces → TimeStep → _floodBoundarySurface classes, for a surface
   representation for each time step. While "floodSurface" and "FloodGroundSurface" are used for water level surface
   and the surface between water and ground, the "FloodClosureSurface" is used to close the enclosure when the flood
   geometry is not a closed volume.




                                        Figure 3: UML Model of the Flood Package

      The valuation package (see Figure 4a) contains an abstract concept, the "_CostObject", that defines the value of
   a particular object. The "AssemblyCostObject" and "BuildingValue" realise the _CostObject for the
   repair/replacement value of building components or the construction cost of the building as a whole. Other
   information describing these classes include issuing institution, date of issue, currency type, etc.


                             (a)                                                                             (b)




                  Figure 4: UML Model of the (a) Valuation Package and (b) MaterialDomain Package




Research@Locate '15                                          83
       The MaterialDomain package contains classes that define the construction materials of the building elements. As
   illustrated in Figure 4(b), this package consists of three kinds of material definition. "Material" class which defines
   a single material that can be directly assigned to a building component or be used as a layer in other material
   classes. "MaterialLayerSet" on the other hand, defines multiple materials as layers. An example here is a wall panel
   which includes the paint, lining and brick materials. The order of layers defines the position of the material in the
   object. "MaterialConstituentSet" is another material definition method which consists of one or more
   "MaterialConstituents" each of which defines the material of a part of component (e.g. "frame" or "glazing" in a
   window) indicated by its particular name.




                                       Figure 5: UML Model of the Utility Package

       Utility package contains the classes related to the interior or exterior utilities of the house. This package is
   illustrated in Figure 5. The utility objects can be defined independently or under a particular system (e.g. electrical,
   water, fuel or HVAC). Each realisation of the abstract "_UtilityObject" class may have a replacement value and a
   material object defined. In terms of the representation, utilities are commonly presented by either a GML solid or
   multiSurface. In this research, for the utilities, the focus was concentrated on the electrical system elements such as
   lights, outlets, meters, switches and distribution boards which are defined under abstract classes "_FlowTerminal"
   and "_FlowController". In addition, elements such as cables can be defined using the "FlowSegment" class that can
   be represented by 3D line segments using a GML Curve. The "_ControlElement" class, on the other hand, is an
   abstract class reserved for future use to represent utility components that are used to impart control over the other
   elements in the system. These classes can be directly mapped to the distribution elements in the IFC data model.

      The building package (see Figure 6) comprises the classes that represent the building and individual or an
   aggregation of building components. The "Site" class represents a parcel characterised by an address and a 2D
   polygon which can contain one or more buildings. Each building has a value associated with it (BuildingValue) and
   can be represented by either its 2D footprint or the aggregation of 3D geometries of its components (e.g. stories). A
   building consists of at least one storey defined by "BuildingStorey" class and may contain utility objects or systems,
   as well as any subtype of the abstract class "_BuildingElement". Each of utility or building elements has a damage
   state and replacement cost attributes associated with them that can be used for cost analysis.
      The building components defined in the model include slabs (either foundation slab or floor represented by
   classes of similar names), structural beams and columns, walls (either simple or complex wall represented by its
   different components using the relationship "consistsOfParts" defined at its supertype), roof (can be defined in the
   same way as wall), stairs (represented as a single component or by railings and stairflights), framing members
   (representing the structural framing of the building other than columns and beams), coverings such as ceiling,
   flooring, soffit, cornices and skirtings), windows (sliding doors are defined similarly), doors, airbricks (vents) or
   any type of void opening. In addition to these components, "BuildingElementPart" defines a class for a generic part
   of any other element. Explicit classes for wall parts ("WallComponentElement" such as the cladding) or covering
   parts (e.g. ceiling insulation and lining) using "CoveringLayerElement" are defined in the model to represent these
   objects.
      In this model, windows and doors are defined either as single object or a combination of a lining (its frame) and
   a minimum of one panel that may have their own geometry, material and cost. "Space" class in this model defines
   those elements for representing the internal (e.g. room) or external (e.g. the backyard) spaces for the building.




Research@Locate '15                                          84
                      Figure 6: UML Model of the Building Package




Research@Locate '15                       85
      On the other hand, "Connection" class here is the supertype for all connections defining a link between a
   _BuildingElement (related element) to another (relating element). The "Mechanical connection", is a specialised
   connection type that employs an additional linking _BuildingElement for the explicit establishment of the
   connection. An example here is the brick cladding to framing connection using "WallTie". The connection between
   the relating and related elements can be further detailed by the geometry type (point, curve, surface or volume) that
   either of the elements or the realising element connects to them. In the wall tie example, the connection is
   simplified by a PointConnectionGeomtry class that has a GML point defined on related and relating elements. The
   connection concept can easily be mapped to its counterpart in IFC model for integration purposes.
      To support extensibility, the building model defines a generic class, "BuildingElementProxy" to be used for
   elements that are not explicitly defined in the current version of the model. A "Slab edge" is an example of this
   element.

   3.5 Data Model Implementation
      Subsequent to the design of the conceptual model discussed in Section 3.4, the logical and physical models were
   developed. XML file was selected in this research to implement the integrated information model. Therefore, the
   physical model was prepared in relation to XML schema specifications. According to the described UML packages
   in Section 3.4 and the designed physical model, an XML Schema was developed. It defines the structure of the
   XML file and rules for definition of objects in it. This schema comprises six namespaces, each of which
   corresponds to and implements one of the UML packages described previously in Section 3.4.


   4 Case Study: Damage Assessment to a House in Maribyrnong
       To verify the application of the designed integrated information model to serve the defined use cases in Section
   3.2, and testing the hypothesis of the research, a case study was conducted in collaboration with Maribyrnong
   Council and Melbourne Water. In this study, damage to a selected house in Maribyrnong was evaluated and
   visualised.
       The required data such as elevation model of the case study area, plans of the building under investigation, and
   the inputs for the flood simulation (e.g. river discharges) were provided by the council and Melbourne Water. The
   building value and the component costs, on the other hand, were obtained from the Office of the Valuer General
   and the Rawlinsons' Australian construction cost handbook 2014. The BIM model of the house was developed
   based on the provided plans and then exported to an IFC file. On the other hand, a 1-in-100 year flood (commonly
   used for planning) was simulated using MIKE 21 simulation package and the outputs (spatial distribution of depth
   and velocity) were exported to 1140 ESRI shape files, each corresponding to a time step. An in-house tool was used
   to extract flood parameters from these files into a single XML file. This XML file was then mapped to the flood
   concepts of the proposed model in Section 3.4 and the flood information, including its geometry and attributes,
   were stored.
       In spite of the previous efforts explained in Section 2.3, there was no tool found that could provide a smooth
   conversion for both geometry and semantics of BIM data to GIS formats. Therefore, a semi-automatic process
   (illustrated in Figure 7) was designed in this research to import building information from IFC into the implemented
   database. In this method, the geometry and semantic information are obtained separately and then combined to be
   stored in the designed database. For geometry extraction, first the IFC elements are converted to ESRI geodatabase
   feature classes using the ArcGIS Interoperability Extension. Then each feature class is converted to CityGML using
   the export function in the extension. As the input objects are not known to the converter engine, the created objects
   in the output are in the form of "GenericCityObject" containing a multiSurface representation of the elements. On
   the other hand, the attributes and relationships between elements are obtained from an exported XML version of the
   IFC file and combined with their geometry using a unique identifier of IFC elements, the "TAG". Having the
   geometry and the semantics of the elements combined, they are then mapped to the proposed data model objects
   and stored in the database.




        Figure 7: Converting the building information from IFC to the database based on the proposed data model



Research@Locate '15                                         86
      The flood parameters and building components were then used to evaluate the mode and level of damage to
   individual components. These calculations are based on the extracted engineering methods for assessing the damage
   (see Section 3.3) implemented in a prototype system. The cost of damage to each component was calculated based
   on its damage level and replacement cost. In addition, the geometry of the building components and colour coding
   were used to visualise the location as well as the level of damage in 3D.


   5 Results and Discussion
       The damage to the building and its components in the case study in Section 4 were assessed by use of the BIM
   and geospatial information together and the implementation of the functions extracted in Section 3.3. Figure 7
   illustrates the study area and the visualisation of flood simulation outputs in 2D and 3D GIS.

                                   (b)                                              (c)




        (a)                                                                                    (d)



    Figure 7: Case study for a house in Maribyrnong: (a) study area, (b) flood simulation output in the area, (c) flood
                 parameters around the house, (d) 3D visualisation of the inundation level for the house

      The damage analysis process showed no structural instability as the load bearing elements remained unaffected.
   However, the building suffered from approximately $51,000 damage to its other components (e.g. doors and
   flooring) from water impacts. This number is the sum of damage costs to individual elements which a subset of
   these costs is presented in Table 2.

                           Table 2: A subset of the damage to individual building components

                                                             Total        Unit of         Unit cost      Total cost
        Building Component                       Count
                                                              units     measurement       (AUD$)          (AUD$)
        Hollow core door (std. 35mm thick)          13         13          each            151.00         1,963.00
        Electric meter box                           1         1            each           855.00          855.00
        Double power point                          30         30          each             45.00         1,350.00
        Timber skirting                             55       137.88          m              15.10         2,081.98
        Carpet flooring                              6       77.181         sqm             58.50         4,515.08
        Timber flooring                             1       101.027         sqm            205.00        20,710.53
        wall lining (gypsum)                        82      418.919         sqm             28.50        11,939.19
        Insulation (Rockwool batts)                 21       171.56         sqm             13.15         2,256.01

      Figure 8 illustrates the 3D visualisation of the location and mode of the damage to building components using a
   3D GIS tool (ESRI ArcScene). Elements in these figures correspond to the items presented in Table 2 and can be
   queried individually. While red represents total damage and replacement is required, green indicates no damage to
   the component. The grey elements is used for putting the turned on damaged items into the building context and
   represent those that user has turned their layer off for damage inspection.




       Figure 8: 3D Visualisation of Damaged Walls (left), Doors (middle) and Flooring (right) in ESRI ArcScene




Research@Locate '15                                         87
      From the above results, all three uses cases defined in Section 3.2 are shown to be successfully satisfied: the
   building structural safety was assessed and the cost of damage to individual components were estimated and
   visualised in 3D. The rich database based on the proposed data model in Section 3.4 was profitably used to integrate
   building information with flood parameters to assess the damage to the selected brick-veneer house at its
   component level and by taking into consideration its unique characteristics. This method provides a more detailed
   output illustrating the details of potential damage to a building that cannot be obtained by the current methods for
   FDA such as damage curves (presenting only a single number for building damage). Therefore, it can potentially
   overcome the limitations of current methods towards providing a better understanding of vulnerabilities in the
   building and facilitating an effective decision making for their treatment.
      A range of stakeholders (e.g. engineering and design firms, councils, referral authorities as well as the building
   owners) can benefit from the outputs of the presented method. A majority of these parties are often challenged by
   similar questions such as "Is a particular development, proposed in an area with risk of flood, resilient to the
   potential risks and should be permitted for construction?" To answer this question, a tool based on the proposed
   integration method for BIM with GIS (similar to what was presented in this study) can facilitate engineers to test
   their designs against the mandated flood performance requirements from Australian Building Code Board. The
   alternative design options or mitigation measures may be considered for treating the vulnerabilities. In here, a cost-
   benefit analysis of their deployment using the proposed method can facilitate the selection of the most effective
   solution. On the other hand, referral authorities and councils can assess the planning and construction requirements
   of the proposed building more effectively by taking into account the details of the risks. Additionally, a feedback
   from the council for this study indicated that in case of disputes between owners and council taken to Victorian
   Civil and Administrative Tribunal (VCAT) in regards to refusal of a particular proposal due to risks, a non-
   engineering language such as the presented 3D visualisation in here can be beneficial for the communication of
   risks to owners for their better comprehension of the basis of the decision. The preliminary feedback from some of
   the aforementioned parties has been positive. However, further systematic investigation is required for
   understanding the value of the additional detailed information presented to them in this work.
      The proposed integration method in this work can complement the use of damage curves for large-scale
   applications to create a multi-scale framework towards a better and more comprehensive understanding and
   treatment of the flood risks at different levels. It can help in improving the resilience of the community towards
   floods and their adverse impacts. The application of the proposed method, however, is limited to one or a few
   buildings where data and computation resources can be feasibly provided. For larger number of buildings at
   municipality or city level, the demand for such high level of detail damage evaluation for decision making would be
   small and other existing methods (e.g. curves) can suitably provide the required decision support.


   6 Conclusions and Future Work
      In this paper, a method for integration of BIM with GIS at the data level using a development of a new data
   model as a profile of GML was presented. The designed data model allows for a unified and consistent storage of
   the detailed representation of the building information alongside the flood parameters and other information (e.g.
   elevation model) in support of the micro-level FDA on buildings. The implementation of the data model and its use
   for assessing the damage to a selected building in a case study in Maribyrnong evidently supported the proposed
   hypothesis in this research: the BIM-GIS integration can facilitate a detailed assessment and 3D visualisation of
   damage costs to a building that is presently not supported by the type of inputs used in the current methods for
   FDA.
      The preliminary feedback from the discussions with engineers and the council has been positive and a number of
   benefits are highlighted. Further research, however, is envisaged to systematically investigate the value of this extra
   and detailed information to the stakeholders involved in detailing the use cases in this research.
      Furthermore, the data model presented in this paper was designed based on the analysis of the requirements for
   one particular construction type. The methodology used in this research can also be used for other building types
   and hazards to extend the data model for all types of buildings towards the development of a comprehensive
   repository of data for analysis of all types of buildings and events.


   References

   Birkmann, J., Cardona, O. D., Carreno, M. L., Barbat, A. H., and Pelling, M. (2013). "Framing Vulnerability, Risk
           and Societal Response: The MOVE Framework." Journal of Natural Hazards no. 67:193-211.
   Christodoulou, S. E., Vamvatsikos, D., and Georgiou, C. (2010). A BIM-Based Framework for Forecasting and
           Visualizing Seismic Damage, Cost and Time to Repair. Paper read at 8th European Conference on Product
           and Process Modelling (ECCPM), at Cork, Ireland.
   CLG (2007). Improving the flood performance of new buildings - Flood resilient construction. Department for
           Communities and Local Government. London.




Research@Locate '15                                          88
   Dollner, J., Baumann, K., and Buchholz, H. (2006). Virtual 3D City Models as Foundation of Complex Urban
             Information Spaces. CORP, Vienna. http://www.realcorp.at/archive/CORP2006_DOELLNER.pdf.
   Eastman, C., Teicholz, P., Sacks, R., and Liston, K. (2011). BIM Handbook: A guide to building information
             modeling fo owners, managers, designers, engineers and contractors. Second ed. New Jersey, NY: Wiley.
   El-Mekawy, M., and Ostman, A. (2010). Semantic Mapping: An Ontology Engineering Method for Integrating
             Building Models in IFC and CityGML. Paper read at 3rd ISDE Digital Earth Summit, 12-14 June, at
             Nessebar, Bulgaria.
   El-Mekawy, M., Ostman, A., and Shahzad, K. (2011). "Towards Interoperating CityGML and IFC Building
             Models: A Unified Model Based Approach." In Advances in 3D Geo-Information Sciences, Lecture Notes
             in Geoinformation and Cartography, edited by Kolbe, T. H., 73-93. Berlin: Springer-Verlag.
   Elmasri, R., and Navathe, S. B. (2011). Database Systems: Models, Languages, Design and Application
             Programming. 6th ed. Boston, MA: Peasrson.
   Geoscience Australia (2014). National Exposure Information System (NEXIS). Available from
             http://www.ga.gov.au/scientific-topics/hazards/risk-impact/nexis [Last Accessed on 17 November 2014].
   Hijazi, I., Ehlers, M., and Zlatanova, S. (2010). BIM for Geo-Analysis (BIM4GEOA): Set Up of 3D Information
             System With Open Source Sofrware and Open Specification. Paper read at 5th International 3D GeoInfo
             Conference, 3-4 November, at Berlin, Germany.
   HNFMSC (2006). Reducing Vulnerability of Buildings to Flood Damage: Guidance On Building In Flood Prone
             Areas. Hawkesbury-Nepean Floodplain Management Steering Committee.
   IAI (2005). IFC for GIS (IFG). Available at www.iai.no/ifg/Content/ifg_use_cases.htm [Last Accessed in 2012].
   Isikdag, U., and Zlatanova, S. (2009a). A SWOT analysis on the implementation of Building Information Models
             within the Geospatial Environment. Paper read at proceedings of the Urban Data Management Society
             symposium 2009, 24-26 June, at Ljubljana, Slovenia.
   Isikdag, U., and Zlatanova, S. (2009b). "Towards Defining a Framework for Automatic Generation of Buildings in
             CityGML Using Building Information Models." In 3D Geo-Information Sciences: Lecture Notes in
             Geoinformation and Cartography, 2009, Part II, 79-96. Springer Berlin Heidelberg.
   Karimi, H. A., and Akinci, B. (2010). CAD and GIS Integration. Edited by Karimi, H. A. and Akinci, B. 1st ed:
             Taylor and Francis Group (CRC Press).
   Li, J., Tor, Y. K., and Zhu, Q. (2006). Research and Implementation of 3D Data Integration Between 3D GIS and
             3D CAD. Paper read at XXIII FIG Congress, October 8-13, 2006, at Munich, Germany.
   Merz, B., Kreibich, H., Schwarz, J., and Thieken, A. (2010). "Review Article: "Assessment of Economic Flood
             Damage"." Natural Hazards and Earth System Sciences no. 10:1697-1724.
   Messner, F., Penning-Rowsell, E., Green, C., Meyer, V., Tunstall, S., and Van der Veen, A. (2007). Evaluating
             flood damages: guidance and recommendations on principles and methods. Integrated Flood Risk
             Analysis and Management Methodologies. Wallingford, UK.
   Nagel, C., Stadler, A., and Kolbe, T. H. (2009). Conceptual Requirements for the Automatic Reconstruction of
             Building Information Models from Uninterpreted 3D Models. Paper read at GeoWeb 2009 Academic
             Track - Cityscapes, 27-31 July, at Vancouver, BC, Canada.
   OGC (2007). OGC Web Services Architecture for CAD, GIS and BIM. Open Geospatial Consortium.
   Pistrika, A. K., and Jonkman, S. N. (2010). "Damage to residential buildings due to flooding of New Orleans after
             hurricane Katrina." Natural Hazards no. 54:413–434.
   Safe (2013). FME Software. Available from http://www.safe.com/fme/ [Last Accessed on August 2013].
   Schulte, C., and Coors, V. (2009). Development of a CityGML ADE for Dynamic 3D Flood Information, Faculty of
             geomatics, Computer Science and Mathematics, University of Applied Sciences Stuttgart, Germany.
   Teorey, T. J., Lightstone, S. S., Nadeau, T., and Jagadish, H. V. (2011). Database Modeling and Design: Logical
             Design. Fifth ed: Morgan Kaufmann.
   Thieken, A., Muller, M., Kreibich, H., and Merz, B. (2005). "Flood damage and influencing factors: New insights
             from the August 2002 flood in Germany." Journal of Water Resources Research no. 41 (12):W12430.
   Van Berlo, L., and Laat, R. (2010). Integration of BIM and GIS: The Development of the CityGML GeoBIM
             Extension. Paper read at 5th International 3D GeoInfo Conference, 3-4 November, at Berlin, Germany.
   Wu, H., Zhengwei, H., and Gong, J. (2010). "A virtual globe-based 3D visualization and interactive framework for
             public participlation in urban planning processes." Computers, Environment and Urban Systems no.
             34:291-298.
   Zhang, X., Arayici, Y., Wu, S., Abbott, C., and Aouad, G. (2009). Integrating BIM and GIS for large-scale facilities
             asset management: a critical review. Paper read at The Twelfth International Conference on Civil,
             Structural and Environmental Engineering Computing, 1-4 September 2009, at Funchal, Madeira,
             Portugal.




Research@Locate '15                                        89