An ontology-based analysis of the industry foundation class schema for building information model exchanges

Robust knowledge sharing frameworks between different stakeholders in a building project is of high priority. Industry Foundation Classes (IFC) provides a rich schema for interoperability through object-based transactions. However, IFC lacks semantic clarity in mapping entities and relationships, resulting in multiple definitions to map the same information between different federated models. The objective of this research is to examine IFC from a perspective of an ontological framework, which can make the IFC definitions more formal, consistent and unambiguous. Different methods of ontological approaches to engineering knowledge are reviewed. Various issues such as the need for a logical framework, the current semantic approaches in the AEC/FM industry, and advantages of building an ontology structure are addressed. A comparative study of the ontology and segments of the existing IFC schema definition are performed. This exercise reveals the ambiguous nature of current IFC definitions and proposes reforms such that data exchanges would be more semantically robust. An ontology would structure the overall interoperability of BIM tools by providing a formal and consistent taxonomy and classification structure for extending IFC and for defining subsets as model view definitions (MVD).     

SpaRSE-BIM: Classification of IFC-based geometry via sparse convolutional neural networks

Information exchange between Building Information Modeling (BIM) tools is challenging, since many applications use their own native data formats. The Industry Foundation Classes (IFC) schema, an open data exchange format for BIM, does not capture the full semantic meaning needed for direct use by different BIM tools and can be prone to information loss due to reduction, simplification, translation and interpretation of the data. Current practice often treats the imported model as a reference and requires a user to remodel the building using the respective application’s native elements. Many BIM object properties are defined by its classification. Inconsistencies in the mapping between native BIM elements and IFC, e.g. due to unsupported export functionality or manual error, can lead to problems when using the model in a downstream application. Recent works demonstrate that neural networks offer a promising possibility to alleviate this issue via classification of the objects contained in a BIM model and suggesting those corrections to the user. However, the computational overhead of these deep learning models, either due to necessary pre-processing of the data or runtime performance of the model, makes it difficult for them to be used in plug-ins or middleware for BIM tools. This work proposes SpaRSE-BIM, a neural network model based on sparse convolutions for the classification of IFC-based geometry and semantic enrichment of BIM models. Experiments are performed on two IFC entity classification benchmark datasets. The results demonstrate that SpaRSE-BIM is significantly more efficient at inference time compared to previous approaches, while maintaining state-of-the-art accuracy. Further experiments explore the applicability of IFC entity classification datasets to the domain of Scan-to-BIM. It can be shown that the feature space of SpaRSE-BIM learns to discern objects in a semantically meaningful way, even in cases where fine-grained subtype information for IFC objects is not available during training.     

An IFC schema extension and binary serialization format to efficiently integrate point cloud data into building models

In this paper we suggest an extension to the Industry Foundation Classes (IFC) model to integrate point cloud datasets. The proposal includes a schema extension to the core model allowing the storage of points, either as Cartesian coordinates, points in parametric space of associated building element surfaces or as discrete height fields projected as grids onto building elements. To handle the considerable amounts of data generated in the process of scanning building structures, we present intelligent compression approaches combined with the Hierarchical Data Format (HDF) as an efficient serialization and an alternative to clear text encoded ISO 10303 part 21 files. Based on prototypical implementations we show results of various serialization options and their impacts on storage efficiency.In this proposal the deepened semantic relationships have been favoured over compression ratios. Nevertheless, with various near-lossless layers of compression and binary serialization applied, a compression ratio of up to 67.7% is obtained for a building model with integrated point clouds, compared to the raw source data. The binary serialization is able to handle hundreds of millions of points, out of which specific spatial and semantic subsets can rapidly be extracted due to the containerized hierarchical storage model and association to building elements. The authors advocate the use of binary storage for sizeable point cloud scans, but also show how especially the grid discretization can result into usable points cloud segments embedded into text-based IFC models.     

Semantics of model views for information exchanges using the industry foundation class schema

The industry foundation classes (IFC) data schema is generic, designed to support the full range of model exchanges needed in the construction industry. For any particular working exchange for some sub-domain of building construction, a set of model view definitions (MVD) is required to specify exactly what information should be exchanged, and in what form and structure the IFC entities are to be used. Defining model view definitions requires principle decisions and workarounds because the IFC itself does not address a number of semantic issues comprehensively. Some of the issues identified and discussed include the typing of objects, instances, geometry, relationships, and rules, which are supported in the IFC schema, and the complexities of exchanging such information accurately between applications. This paper advances the idea of MVD Concepts as an object-oriented and modular mechanism for embedding semantic meaning in model views. We conclude that although the IFC product model schema is richly expressive, it lacks formal definition of its entities, attributes, and relationships. To achieve standardized and re-usable model views, further research towards a modular and logical framework based on formal specification of IFC concepts is recommended. This research is expected to impact the overall interoperability of applications in the building information modeling realm.     

An iterative reference mapping approach for BIM IFCXML classified content compression

Industry Foundation Classes (IFC) and Industry Foundation Classes XML (IFCXML) are widely accepted data frameworks and formats for information storage and exchange among building information models (BIM). IFCXML are comprehensive and compatible with the major BIM platforms; however, many studies suggest their complex structure often results in redundancy and inflexibility. Researchers have proposed various IFC compression methods to reduce file size and restructure data organization, such as partial model extraction, Solibri IFC Optimizer, and ACC4IFC. However, simplification often results in missing information or data leakage, and there has never been a compressor specific to IFCXML. To overcome these issues, this study proposed a conservative compression method that removes duplicated information while maintaining the data structure of IFCXML through an iterative reference mapping method. Based on the data structure and geometry of IFCXML, the algorithm identified three kinds of duplicate information: independent entity duplication (IED), cross-reference entity duplication (CED), and property-set entity duplication (PED). To validate the proposed compressing method, this study conducted a validation test on six typical BIM models and benchmarked with other existing compressors (Solibri IFC Optimizer and ACC4IFC). The outcomes suggested that the proposed model could compress IFCXML files by 18%-59% without losing information.     

Object-oriented query language access to relational databases: A semantic framework for query translation

This research investigates and approach to query processing in a multidatabase system that uses an objectoriented model to capture the semantics of other data models. The object-oriented model is used to construct a global schema, defining an integrated view of the different schemas in the environment. The model is also used as a self-describing model to build a meta-database for storing information about the global schema. A unique aspect of this work is that the object-oriented model is used to describe the different data models of the multidatabase environment, thereby extending the meta database with semantic information about the local schemas. With the global and local schemas all represented in an object-oriented form, structural mappings between the global schema and each local schema are then easily supported. An object algebra then provides a query language for expressing global queries, using the structural mappings to translate object algebra queries into SQL queries over local relational schema. The advantage of using an object algebra is that the object-oriented database can be viewed as a blackboard for temporary storage of local data and for establishing relationships between different databases. The object algebra can be used to directly retrieve temporarily-stored data from the object-oriented database or to transparently retrieve data from local sources using the translation process described in this paper.     

IFC 标准领域层实体扩展方法研究

根据建筑行业数据共享与交换的实际需求以及IFC 标准领域层实体信息缺失的现 状,提出扩展IFC 标准领域层实体的思路,以电气专业的实体为例,详细介绍了扩展IFC 标准 领域层实体的具体方法：通过编辑IFC 标准的EXPRESS-G 视图将新实体添加入IFC 标准框架 内,利用BIM 软件得到新实体的IFC 文件,并在上海交大BIM 团队自行研发的SJTUBIM 平台 上对扩展的实体进行验证。证明了扩展IFC 实体方法的可行性。本文的扩展方法可以促进IFC 标准实现对建筑全生命周期内各种数据信息描述的完整性。随着新型设备的不断增加,IFC 实 体的扩展将会大大推动工程信息的数字化表达,促进工程信息的有效交流和转换。     

Reasoning about ER models in a deductive environment

In this paper we present an approach to represent schema information, application data and integrity constraints as a logic program in form of Datalog. The schema information is supplied as an enhanced entity relationship (EER) model which is transformed by a one-to-one mapping into a set of ground facts. The application data corresponding to the schema is also represented by ground facts in a single table. In order to check whether the application data conforms to the given schema, generic functional and inclusion dependencies are introduced, which can be mapped into concrete dependencies using the schema information. The concrete dependencies are used for checking the consistency between application data and the schema. The formulation of the constraints based on functional and inclusion dependencies led to a small extension of the EER model by allowing identifying attributes in relationship types. This extension leads to both simpler constraints and simpler EER application models.Furthermore, we provide a meta EER model which can be used to check whether the application EER model is a structural valid EER model. Any application EER diagram is an instance of the meta EER diagram which can be specified using the proposed application data representation. The same integrity rules can be used to check the conformance between the application data and the application EER diagram, the meta EER diagram and the application EER diagram, and finally it can be used to check the meta EER model itself.     

Mapping of industry building product model for detailed thermal simulation and analysis

Industry Foundation Classes (IFC) is an emerging data standard that promotes the interoperability of digital building product object models, or building product models (BPMs). Implementing IFC-based applications allows reducing data duplication, especially in the aspect of building geometry. With appropriate data mapping engines, an existing BPM may be readily used for performance-based simulation which requires significantly less effort compared with the traditional means. As a result, it is possible to make use of many available proprietary tools to provide additional services such as early-stage building design support. SEMPER-II (S2), which is an active, multi-domain, space-based, object-oriented design support tool for integrated building performance computing, was developed before the IFC standard was established. In order to perform building performance simulations based on the IFC compliant data models expressed through the eXtensible Markup Language (XML) based formats, an add-on data mapping engine has been developed as a front-end application in S2. The data mapping engine extracts all necessary information embedded in the XML data files, which is obtained directly from IFC compliant CAD drawings, and converts the data into the internal data format of S2.This process demonstrates a seamless link between an IFC compliant industry building product model (e.g. CAD) and the Shared Object Model (SOM) of S2 to facilitate building performance simulations.     

装配式建筑自上而下设计信息协同与模型构建

为顺应国家建筑产业化、智能化发展的政策引导,针对当前装配式建筑专业信息缺乏关联、模 型利用不充分、数据传递效率低下等问题,提出基于建筑信息模型(BIM)技术的自上而下设计方法。以装配式 建筑的设计阶段为切入点,详细阐述了基于 BIM 技术的装配式建筑自上而下设计流程。结合装配式建筑的标 准化构件设计和组装特点,提出一种基于自上而下设计的装配模型,并从层级和专业 2 个角度描述了模型的架 构。针对各专业模型传递时的数据信息标准化、一致性问题,通过工业基础类(IFC)标准对装配模型进行实体和 属性集的扩展,提出基于 IFC 标准的各专业、各阶段的自上而下设计信息协同。经实例验证了 IFC 扩展装配模 型的自上而下设计可行性,为装配式建筑的协同设计提供了有益的方法借鉴。     

Towards an integrated Flood Information System: Centralized data access,analysis, and visualization

The Iowa Flood Information System (IFIS) is a web-based platform developed at the Iowa Flood Center (IFC) in order to provide access to flood inundation maps, real-time flood conditions, flood forecasts, flood-related data, information, applications, and interactive visualizations for communities in Iowa. The IFIS provides community-centric watershed and river characteristics, rainfall conditions, and stream-flow data and visualization tools. Interactive interfaces allow access to inundation maps for different stage and return period values as well as to flooding scenarios with contributions from multiple rivers. Real-time and historical data of water levels, gauge heights, hourly and seasonal flood forecasts, and rainfall conditions are made available by integrating data from NEXRAD radars, IFC stream sensors, and USGS and National Weather Service (NWS) stream gauges. The IFIS provides customized flood-related data, information, and visualization for over 1000 communities in Iowa. To help reduce the damage from floods, the IFIS helps communities make better-informed decisions about the occurrence of floods and alerts communities in advance using NWS and IFC forecasts. The integrated and modular design and structure of the IFIS allows easy adaptation of the system in other regional and scientific domains. This paper provides an overview of the design and capabilities of the IFIS that was developed as a platform to provide one-stop access to flood-related information.     

An intelligent simulation system for earthquake disaster assessment

This paper presents an intelligent simulation system for an earthquake disaster assessment system based on a development platform of a Geographic Information System (GIS) and Artificial Intelligence (AI). This system is designed to identify the weakness of the structure and infrastructure system in pre-earthquake conditions, quickly assess earthquake damage and make an intelligent emergency response for the public and government during the earthquake and post-earthquake. The system includes the following functions: intelligent seismic hazard assessment, earthquake damage and loss evaluation, optimizing emergency response and post-earthquake recovering plan. The principle, design criteria, structure, functions and test results of this system are described in this paper. Based on its functional characteristics, this system is composed of four parts: an information database, analytical modules, an intelligent decision-making sub-system and a friendly user interface. There are 132 coverages and 78 analytical modules included in the information database and analytical modules. With this system, seismic disaster mitigation strategies can be verified during a pre-earthquake, and be executed at the time of an earthquake and post-earthquake; the earthquake resisting capacities for an entire city and all of its communities can be greatly enhanced. To check its reliability and its efficiency, this system has been tested based on a scenario earthquake event in one city, and the related results have also been given in this paper. At the present, this system has been installed and used in Daqing City, China. After running for almost 10 years, this system has successfully been used in rehearsing of seismic disaster mitigation and post-earthquake emergency response. Simultaneously, an optimizing aseismic retrofitting plan in Daqing City has been executed based on results from this system.     

Semantic interoperability in building design: Methods and tools

Semantic interoperability is a crucial element to make building information models understandable and model data sharable across multiple design disciplines and heterogeneous computer systems. This paper presents a new approach and its software implementation for the development of building design objects with semantics of interoperable information to support semantic interoperability in building designs. The novelty of the approach includes its incorporation of building design domain ontology, object-based CAD information modeling, and interoperability standard to make building information models and model data semantically interoperable. A set of methods are proposed to address the issues of object-based building information representation compliant with the Industrial Foundation Classes (IFC); extension of IFC models with the supplementary information; and semantic annotation of the interoperable and extensible information sets. The prototype implementation of these methods provides a set of Web-enabled software tools for effectively generating, managing, and reusing the semantically interoperable building objects in design applications of architectural CAD, structural analysis, and building code conformance checking.     

Methods for the Automated Assignment and Comparison of Building Damage Geometries

Condition assessment of structures supports effective repair, restoration or reconstruction works on buildings of infrastructural or cultural importance and is therefore an important contribution to building and infrastructure sustainability. Due to increasing ageing and external influences continuous monitoring is obligatory to maintain the structures. Throughout the entire life cycle, digital scans of changing damages and the building geometry, up to the degree of a digital twin, can be acquired using modern inspection methods. This allows for the automation of condition assessment processes to locate, quantify and predict damage progression at a structure related to building information models. However, the usual inspection documentation as performed in the past neither includes an assignment of damages to digital building models nor relates the history of recordings to a damage entity, which consequently makes a direct condition state comparison unfeasible.The paper presents voxel based methods for the automated assignment of geometrical representations of damages to elements of a corresponding building model as well as to past damage scans, which describe the same damage entity. Furthermore, the comparison and computation of discrete geometric changes based on the assignments is shown. Additionally, the clustering of scanned damage geometries into interest areas for the usage in planning processes for further inspections is presented. The resulting set of methods enables an automated condition comparison of damages on each surveyed state of the structure and supports the integration of inspection data to building information models.     

基于IFC 标准的结构分析模型构件偏心问题研究

数据标准是解决信息共享与交换问题的基础。IFC 作为buildingSMART 联盟发布 的建筑信息模型数据交换的国际标准,用来实现建筑全生命周期中不同专业、不同阶段各软件 之间的协同工作。目前在工程建设行业多专业的配合过程中,建筑与结构专业的信息交互最为 迫切。在结构专业领域,构件偏心问题对结构模型的分析有着重要影响。基于建筑信息模型数 据共享与交换的IFC 标准,针对结构分析软件之间的模型数据转换问题,通过以SGF 结构通用 文件格式为基础的数据转换平台,提取偏心构件的数据表达并设计数据转换算法,运用C++编 程语言,实现结构构件偏心数据的IFC 表达。     

BIM 模型相似度计算方法

针对从业者不论是想从本地模型库还是线上共享网站获取所需的BIM 模型只能靠 逐个查找、人工识读的方法,而模型的数量越来越多,获取符合需求的模型需要花费大量的时 间和人力的问题,提出了一种构件级BIM 模型相似度计算方法。从模型的构件出发,以BIM 通用交互格式工业基础类(IFC)文件作数据源,以通用数据标准IFC 2×3 为数据基础,首先提取 模型中构件的几何信息、语义信息等,并利用改进的方向包围盒(OBB)碰撞检测算法查找相连 构件;然后以构件为顶点、构件间连接关系为边将BIM 模型构建为邻接图模型,并用图编辑距 离算法计算邻接图模型的编辑距离;最后即可计算出不同模型之间的相似度。该方法以构件级 BIM 模型的相似度为依据可以大大提升BIM 模型的检索速度与准确率。     

Incorporation of BIM-based probabilistic non-structural damage assessment into agent-based post-earthquake evacuation simulation

Earthquakes can cause severe damage to structural and non-structural elements of buildings; consequently, they pose high risks to human lives. To mitigate such risks, attention has been paid to enhancing the indoor environment for increased building safety. Yet little effort has been made to assess a building occupants' evacuation behaviors in response to damage to the indoor environment. This paper addresses this issue with a novel simulation framework that couples human behaviors with changes to the indoor building environment during post-earthquake evacuation. In particular, we present a building information modelling (BIM)-based prototype that simulates seismic damage to the non-structural indoor elements and visualizes its impacts on evacuation using a color-coded heat map. The simulated damage is then used as input to an agent-based model for post-earthquake evacuation. Using a probabilistic method to assess the non-structural elements' damage states, we are able to evaluate the impact of indoor damage on the evacuation process. We performed a trial of our prototype for a hypothetical earthquake in an educational building. The results revealed how the average evacuation time would increase as the earthquake intensity increases (from 38.6 s for the no-damage scenario to 122.9 for the highest-damage scenario). The proposed prototype has the potential to be joined with other tools, such as finite-element-based simulation, to incorporate structural analysis as well. Planners and designers can explicitly use our model's output to analyze the post-earthquake evacuation with the indoor non-structural damage to assess different building design geometries that increase the chances of a suitable evacuation process.     

基于遥感影像不透水层估算的震后城区损坏面积评估

地震灾害评估对于抗震救灾具有重要的现实意义,传统的灾害评估方法大多基于震后实地的统计数据进行,在数据获取的现势性和灾害评估效率方面存在问题,针对这一不足,结合遥感数据的特点,提出了一种基于遥感不透水层估算的地震灾后城区损坏面积评估方法。该方法首先对地震前后玉树地区的两幅中分辨率遥感影像进行预处理,然后基于V-I-S模型,利用线性光谱混合分析方法,分别对地震前后震区遥感影像进行端元提取,获得不透水层的丰度图,最后通过计算地震前后不透水层像元个数,进行地震灾后城区损坏面积的评估。通过精度分析可以看出:该方法可以快速及时地获〖JP3〗取城市区域建筑物、公路等重要地物的宏观损坏面积情况,为灾后重建和震后决策提供了一定的依据。     

Shared computer-aided structural design model for construction industry (infrastructure)

The current interaction between participants in a construction project requires much time and is often a cause of mistakes and misunderstandings. Improvement of this interaction may therefore contribute to an improvement of the construction process as a whole. The lack of interoperability is the main problem behind such interaction drawbacks. In this paper, an infrastructure for a technology transfer model, namely Shared Computer-Aided Structural Design (sCAsD) model, is developed. It is built upon three basic building blocks: the Standard for the Exchange of Product Model Data (STEP, ISO-10303) Parts 104 and 107, the CIMsteel Integration Standard (CIS/2.0) resources, and the Industry Foundation Classes (IFC) standard that is being developed by the International Alliance for Interoperability (IAI). The sCAsD model is an extension for the structural domain/view of the IFC model, providing professional standardization within the synergy effect of the IFC. The model infrastructure is explained and discussed in terms of model schemata. In addition, model feasibility is studied within two assessments for model schemata and model realization in the construction industry. The former assessment has verified the robustness and effectiveness of the model through using a model interface in data handling within an application of an integrated earthquake simulation. Meanwhile, the assessment of model realization has validated the roadmap of model implementation in the construction industry through IAI. The model has been accepted as a formal IAI project, namely ST-7, and is being supported by IAI Japan chapter.