A short review of BIMs Umit Isikdag University of Salford

Introduction Fragmentation is a key feature of the construction industry Traditional nature of the industry is extremely ‘document- centric’ with construction project information being captured predominately in documents The nature of the industry has resulted in significant barriers to communication between the stakeholders and also between different software developed for various different purposes.

Introduction In recent years, Building Information Modelling has become an active research area in order to tackle the problems related to information integration and interoperability Today, Building Information Modelling is promising to be the facilitator of integration, interoperability and collaboration for the future of the construction industry

Background(Early CAD to ISO 10303) During the 1970s CAD companies realised the need for data exchange which was being expressed by industry. In response, they developed some low level methods to read and write data from applications.As an implementation of methods some proprietary file formats have emerged. Drawbacks of these formats: They were controlled by the companies who had implemented them therefore they could change at any time. When a new file format is introduced a number of N*(N-1) data translators needed to be written (or 2*(N-1) more needs to be added to existing translators) in order to exchange data between N applications.

ISO STEP The emergence of STEP - ISO 10303: Industrial Automation Systems and Integration – Product Data Representation and Exchange - was a result of the issues associated with the shortcomings of CAD data translation The distinction between data sharing and exchange is clearly identified during STEP development efforts and in addition the STEP standard identified four implementation levels for data storage and exchange. Ship production & Aerospace Industry are among first users of STEP

Introduction to BIMs BIMs of today have emerged as a result of an evolution from de-facto drawing exchange formats through (STEP based) semantic AEC information models Most of these semantic models adopted Product Modelling concepts by being enablers of communication, interpretation and processing of information, thus many of them are also known as Building Product Models. Similarly, most of them such as CIS2, IFC are defined using STEP (ISO 10303) description methods (EXPRESS), thus these models are also referred to as Building Information Models, deriving from the term Information Modelling that is used in STEP resources.

BIMs: Recent definitions Building Information Modelling can be defined as a new way of creating, sharing, exchanging and managing the information throughout the entire building lifecycle(NBIMS,2007). A BIM is a computable representation of all the physical and functional characteristics of a building and its related project/life-cycle information, which is intended to be a repository of information for the building owner/operator to use and maintain throughout the life-cycle of a building.(NBIMS,2006).

In recent definitions the BIM is interpreted as... An information management methodology for the entire construction life cycle. A shared knowledge resource/ a shared information model.

Our understanding : (~US NBIMS) An information backbone for facilitating the sharing of information throughout the lifecycle of a building

BIMs:The main characteristics 3D/Object Oriented: Most of the BIMs are defined in an object-oriented nature where building element geometries are defined in 3D. Vendor Neutral/Interoperable: BIMs are developed with the aim of effective information exchange and sharing. Interoperability is a necessity to bring together a set of diverse stakeholders working within in a complex supply chain and project environment. Enables Interoperability: BIMs are developed to overcome the problem of insufficient interoperability, thus this appeared as a natural characteristic. Data-rich/Comprehensive: BIMs are data rich and comprehensive as they aim to cover all physical and functional characteristics of the building. Covers various phases of the project life-cycle: State of the art BIMs cover various phases of the project life-cycle through the use of different view and applications. The objects of the model can be in different states in different phases of the lifecycle in order to represent the N dimensional information about the building. Spatially-related/Rich in semantics: Spatial relationships between building elements are maintained in the BIMs in a hierarchical manner. BIMs store a high amount of semantic (functional) information about the building elements. Supports view generation: The model views are subsets or snapshots of the model that can be generated from the base information model. BIMs therefore support view generation.

Sharing and Exchanging Information with BIMs

ISO (Distiction between Data Sharing and Exchange) Data exchange is defined as the transfer of information from one software system to another via a medium that represents the state of information at a single point in time. Data sharing provides a single logical information source to which multiple software systems have access. In data sharing, the information source may be realised as a database management system, a specialised file system or a combination of the two. The characteristics that distinguish data sharing from data exchange are the centrality of the data and versioning control.

ISO Implementation Levels File exchange level: EXPRESS-defined product data is passed between applications using flat files.(P-21) Working form level: The software in working form level has all features of level one in addition to the ability to manipulate data.(SDAI) Database level: This level has all features of level two along with the ability to work with the data stored in a database. Knowledgebase Level: Implementations of this level will have all features of level three and should be able to reason about the contents of the database. This level has never been implemented.

The role of BIM –Model Views-

Model Views An Information Model derived from a BIM to facilitate the exchange of shared product information. The Model View should not be a superset of a predefined (base) information model (BIM). The view can be a subset of the model or the model itself. The view can provide a snapshot of the information model (or its subset).

Model Views Model views can be generated from physical files or databases by using application, database and web interfaces. Model Views can be : Persistent Transient

Model Views The persistent model views  generated by model translation there is a need to exchange a subset of BIM between various different domains there is a need to exchange a snapshot of the BIM in one stage of the project. The transient views  generated by queries an application environment requires a subset of BIM entities in run-time. Express-X/ XSL /SQL /DB APIs can be used to generate the Model Views

The envisioned role of BIMs in the future of AEC industry

TOWARDS THE IMPLEMENTATION OF BUILDING INFORMATION MODELS IN GEOSPATIAL CONTEXT Umit Isikdag University of Salford

Motivation. (Construction Industry) In construction industry: A BIM standard, IFC, is maturing as a model in supporting various processes in the construction life cycle. Recent industrial IT visions indicated that GIS can assist in site selection process. In order to use GIS for site selection building information needs to be transferred from BIMs into geospatial environment.

Motivation (Urban Management) In urban management: Representing and managing urban environment in 3D is becoming an apparent need. Some urban management tasks, i.e. emergency response management detailed visualisation of urban fabric require a high level and volume of geometrical and semantic information about buildings. High level and volume of building information needs to be transferred into geospatial environment in order to accomplish these tasks efficiently.

Background As CAD systems and GIS are developed for different domains and purposes, they interpret the world differently. Today, Building and Geospatial Models can represent: Form (Geometry, Spatial Relations) Semantics (Meaning, Function) Until recently the efforts towards integrating CAD systems and GIS (from CAD to GI direction) demonstrated: The transfer of building geomtery from CAD models to geospatial environment (mostly in 2D, and rarely in 3D). In contrast, semantic information has not been transferred into geospatial environment.

Research Problem Despite the fact that: BIMs are maturing in the industry The use of GIS, can support site selection There is a need for high level and amount of building information in urban management. –Several processes in construction and urban management can not become fully automated, due to the lack of required level and amount of information about buildings, in geospatial domain.

Aim and Objectives of the research The research aimed: To assess the applicability and benefits of an implementation of a Building Information Model in geospatial context. Objectives of the research were: To investigate if site selection and fire response management processes can benefit from an implementation of a BIM in geospatial context.

Methodology 1.Use case scenarios are developed in order to investigate the possible use of IFC models in site selection and fire response management processes. 2.Software components are developed to transfer the required level of form and semantic information from the IFC model to the geospatial environment. 3.Software components are then verified through unit and component testing and validated through system testing and semi-structured interviews.

Summary of the techincal developments

Schema Level Model views (by Express-X) EDM /ESRI Geodatabase Packages as COM+ components Inp.Pro.Pack. (CSG/Sweeping) to (BRep) Components designed in form of separate packages (flexible design)

Persistent Schema Level Model View (Aspect Model) IFC Conpectual GI Model Transient Temporary Object Model Persistence Implementation ESRI Shapefiles Persistence Implementation ESRI Geodatabase

Schema Level Model View (Highest Level Express-G Diagram) IFC Schema Persistent Schema Level Model View Data Mapping Persistent Schema Level Model View IFC Object oriented ISO DB

Geometrical Transformation (Translation and Rotation Operations from Local to Global in R 3 ) CSG + Sweeping to BREP Conversion Acquire semantic information Persistent Schema Level Model View Transient Temporary Object Model

Persistent Schema Level Model View Transient Temporary Object Model

Geometric transformation is implemented for 6 different element types

Sweeping operations to create swept solids

Every element is located relatively (to its spatial container) Transformation operations to locate the building elements in absolute global coordinates(R 3 )

CSG Operations (Mainly Half Plane Intersection)

Conpectual GI Model Transient Temporary Object Model Persistence Implementation ESRI Shapefiles Persistence Implementation ESRI Geodatabase

Conpectual GI Model

Approach for representation Number of features (geospatial obejcts) used to construct a 3D building element Parts used to construct the feature (geospatial object) Used in representing 1N1N1Bm,Clm,Dr,Wn. 1NMNMWl,Sl,Fp Approaches implemented for the representation of building elements

ESRI Shapfile Representation

ShapeStorey IdBeam Id PolygonZ N1 implementation for represeting beams 1 Beam consists of N (6) Features that consist of 1 Part (i.e outer ring)

ESRI Geodatabase Representation

1NM implementation for representing walls 1 Wall consists of N Features each consist of M Parts

XT0, YT0 = the coordinates of the origin point of the source coordinate system, expressed in the target coordinate system. 1+dS = the length of one unit in the source coordinate system expressed in units of the target coordinate systm; q = the angle about which the axes of the source coordinate system axes must be rotated to coincide with the axes of the target coordinate system axes (counter- clockwise is positive). Alternatively, the bearing of the source coordinate system YS-axis measured relative to target coordinate system north.

Innovations: Knowledge Innovation Conceptual Innovation Technical Innovation

Conceptual Innovation in Research A framework for implementing Building Information Models in geospatial context is proposed and used. The framework demonstrated: Use of a information model server store and manage BIMs Use of a Model View to obtain information from BIMs Use of software components to integrate data layers of two information domains Use of different output models and approaches when creating 3D geospatial objects

Technical Innovation The research demonstrated that: Building Information Models can be implemented in geospatial environment. Building information can be stored in geospatial envirionment by using different geospatial data models.

Technical Summary The exchange of information between BIM and GIM needs address the following aspects Transfer ofBIM of today3D GIM of todayIsikdag,2006 Form3D Geometry BIM  Geo-relational models and spatial databases Relationships of Form Spatial RelationshipsRelationships in 3D Topological Models Representation of spatial relationships in geospatial object attributes MeaningObject Types Object Attributes Object Types Object Attributes Representation of meaning in object geospatial attributes FunctionObject Attributes Representation of function in object attributes Functional Constraints Object Attributes Topological Rules -

Technical findings of the research Using an Model View increases run-time performance of an information system that is designed to process BIMs and it also facilitates the system development process. There may be a need for geospatial data models that can represent 3D objects more efficiently.

Thank you very much for your interest.