Dimensional reduction of 3D building models using graph theory and its application in building energy simulation

Since the various people involved in the design process for a building project tend to hold conflicting views, this inevitably leads to a range of disparate models for planning and calculation purposes. In order to interpret the relevant geometrical, topological and semantical data for any given building model, we identify a structural component graph, a graph of room faces, a room graph and a relational object graph as aids and explain algorithms to derive these relations. We start with a building model by transferring its geometrical, topological and semantical data into a volume model, decomposing the latter into a so-called connection model and then extracting all air volume bodies and hulls of the model by means of further decomposition into elementary cyclic connection components. The technique is demonstrated within the scope of building energy simulation by deriving both a dimensionally reduced object model required for setting up a thermal multizone model and a geometrical model for defining single or multiple computational fluid dynamic domains in a building together with incidence matrices correlating these models. The algorithm is basically applicable to any building energy simulation tool.

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.     

Dealing with digital traces: Understanding protective behaviors on mobile devices

With increasingly digitization, more and more information is collected from individuals and organizations, leading to several privacy concerns. These risks are further heightened in the mobile realm as data collection can occur continuously and ubiquitously. When individuals use their own devices in work settings, these issues become concerns for organization as well. The question then is how to ensure individuals perform proper information protection behaviors on mobile devices. In this research, we develop a model of mobile information protection based on an integration of the Theory of Planned Behavior and the information privacy literature to explore the antecedents of the attitude of individuals towards sharing information on their mobile devices, their intentions to use protective settings, and their actual practices. The model is tested with data from 228 iPhone users. The results indicate that mobile information protection intention leads to actual privacy settings practice, and that attitude towards information sharing and mobile privacy protection self-efficacy affect this intention. Determinants of attitude towards information sharing include mobile privacy concern and trust of the mobile platform. Finally, prior invasion experience is related to privacy concern. These findings provide insights into factors that can be targeted to enhance individuals’ protective actions to limit the amount of digital information they share via their smartphones.     

Merging BIM and GIS using ontologies application to urban facility management in ACTIVe3D

This article presents the research work done in order to reduce the gap of heterogeneity between Geographic Information System and Building Information Models. The goal is to extend a platform dedicated to facility management called ACTIVe3D. We want to enlarge its scope to take into account the management of urban elements contained in the building environment, as well as other buildings. The particularity of the platform is that data can be accessed either by a semantic view or through a 3D interface. The SIGA3D project describes a set of processes that aims, for all the stakeholders of urban projects, to manage pieces of information through all the lifecycle of construction projects. To solve the heterogeneity problem between BIM and GIS, we developed a semantic extension to the BIM called UIM (Urban Information Modeling). This extension defines spatial, temporal and multi-representation concepts to build an extensible ontology. The knowledge database can be populated with information coming from standards like IFC and CityGML. This information system has been adapted and implemented into the existing platform and is today fully operational and used by thousands of users.     

Crowd simulation-based knowledge mining supporting building evacuation design

Assessing building evacuation performance designs in emergency situations requires complex scenarios which need to be prepared and analysed using crowd simulation tools, requiring significant manual input. With current procedures, every design iteration requires several simulation scenarios, leading to a complicated and time-consuming process. This study aims to investigate the level of integration between digital building models and crowd simulation, within the scope of design automation. A methodology is presented in which existing ontology tools facilitate knowledge representation and mining throughout the process. Several information models are used to integrate, automate and provide feedback to the design decision-making processes. The proposed concept thus reduces the effort required to create valid simulation scenarios by applying represented knowledge, and provides feedback based on results and design objectives. To apply and test the methodology a system was developed, which is introduced here. The context of building performance during evacuation scenarios is considered, but additional design perspectives can be included. The system development section expands on the essential theoretical concepts required and the case study section shows a practical implementation of the system.     

Information disclosure on mobile devices: Re-examining privacy calculus with actual user behavior

The use of mobile applications continues to experience exponential growth. Using mobile apps typically requires the disclosure of location data, which often accompanies requests for various other forms of private information. Existing research on information privacy has implied that consumers are willing to accept privacy risks for relatively negligible benefits, and the offerings of mobile apps based on location-based services (LBS) appear to be no different. However, until now, researchers have struggled to replicate realistic privacy risks within experimental methodologies designed to manipulate independent variables. Moreover, minimal research has successfully captured actual information disclosure over mobile devices based on realistic risk perceptions. The purpose of this study is to propose and test a more realistic experimental methodology designed to replicate real perceptions of privacy risk and capture the effects of actual information disclosure decisions. As with prior research, this study employs a theoretical lens based on privacy calculus. However, we draw more detailed and valid conclusions due to our use of improved methodological rigor. We report the results of a controlled experiment involving consumers (n=1025) in a range of ages, levels of education, and employment experience. Based on our methodology, we find that only a weak, albeit significant, relationship exists between information disclosure intentions and actual disclosure. In addition, this relationship is heavily moderated by the consumer practice of disclosing false data. We conclude by discussing the contributions of our methodology and the possibilities for extending it for additional mobile privacy research.     

基于区块链的建筑信息模型图纸多人协同创作系统

建筑信息模型(BIM)图纸多人协同创作在大型建筑项目中很重要,而现有的基于Revit等建模软件或云服务的BIM图纸多人协同创作方法存在BIM图纸版本混乱、不易溯源以及数据安全风险等问题.针对这些问题,设计了一种基于区块链的BIM图纸多人协同创作系统.该系统采用链上链下协同的存储方式,使用区块链和数据库分别存储BIM图纸...     

Vagueness visualization in building models across different design stages

The iterative and developing nature of designing a building involves the specification and handling of vague, imprecise, and incomplete information. A crucial factor for mitigating the impact of these uncertainties on the decision-making process is to effectively quantify and communicate them among the project stakeholders. The interactive visualization of 3D building models provides great support for evaluating building designs. However, the currently available visualization methods of the available authoring tools do not incorporate the potential uncertainties associated with the geometric and semantic information of building elements. Currently, building models appear precise and certain, even in the early design stages, which can lead to false assumptions and model evaluations, affecting the decisions made throughout the design stages. Hence, this paper presents a set of visualization approaches, including intrinsic, extrinsic, animation, and walkthroughs, that have been developed to present the uncertainties associated with the building elements’ information. The efficiency of the approaches developed in this study was evaluated through an online survey and interviews. More specifically, the approaches were compared in terms of intuitiveness, applicability, and acceptance. The evaluation results positively indicated the participants’ ability to understand the amount and impact of the uncertainties on the design by using the developed approaches.     

An efficient feature selection method for mobile devices with application to activity recognition

This paper presents a feature selection method for data classification, which combines a model-based variable selection technique and a fast two-stage subset selection algorithm. The relationship between a specified (and complete) set of candidate features and the class label is modeled using a non-linear full regression model which is linear-in-the-parameters. The performance of a sub-model measured by the sum of the squared-errors (SSE) is used to score the informativeness of the subset of features involved in the sub-model. The two-stage subset selection algorithm approaches a solution sub-model with the SSE being locally minimized. The features involved in the solution sub-model are selected as inputs to support vector machines (SVMs) for classification. The memory requirement of this algorithm is independent of the number of training patterns. This property makes this method suitable for applications executed in mobile devices where physical RAM memory is very limited.An application was developed for activity recognition, which implements the proposed feature selection algorithm and an SVM training procedure. Experiments are carried out with the application running on a PDA for human activity recognition using accelerometer data. A comparison with an information gain-based feature selection method demonstrates the effectiveness and efficiency of the proposed algorithm.     

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).     

A method for automatic generation of fuzzy membership functions for mobile device’s characteristics based on Google Trends

While creating a framework for adaptive mobile interfaces for m-learning applications we found that in order to ease the use of our framework we needed to present the mobile device characteristics to non-expert users in a easy to understand manner. Using fuzzy sets to represent the characteristics of mobile devices, non-expert developers such as teachers or instructional designers can actively participate in the development or adaptation of the educational tools. To be able to automatically generate the fuzzy membership functions of the sets we needed the data of the mobile device market, regrettably this information is not publicly available. To tackle this problem we have developed a method to estimate the market share of each mobile device based on the popularity metrics recovered from Google Trends and then we use that estimated value as the input to generate the fuzzy set of each characteristic. The proposed method allows us to not only model the state of the market in different periods of time, but also to localize the results to adapt them to the mobile market of specific countries. In this paper we will describe the proposed algorithm and we will discuss the obtained results.     

Ownership versus on-campus use of mobile IT devices by university students

This study investigated ownership and on-campus use of laptops, tablets, and smartphones, using survey information on Dutch university students. We show that 96% of students own at least one of these mobile IT devices (i.e., a laptop, tablet, or smartphone). Using econometric modelling, we also show that student income, parental income, gender, immigrant parents, and household type (e.g., living with parents) have a statistically significant but small effect on mobile IT device ownership. The demand for tablets is relatively income inelastic, and the demand for laptops and smartphones extremely so. Therefore ownership rates are high for all student groups, including lower income students. However, students leave their laptops (and tablets) at home most of the time, mainly because they find it cumbersome to carry a laptop, and the vast majority of students hold the opinion that abolishing computer labs while facilitating laptop use is a bad idea, despite the didactical advantages this may have during lectures. Thus, it appears that the current high ownership rates of mobile IT devices by no means imply students' preference or support for university Bring Your Own Device (BYOD) strategies.     

基于BIM管网漏水事故处理的本体建模与推理

建筑行业经历了由纸质的图纸到二维的CAD制图,再到以构件为基础的BIM建筑信息模型的变迁,信息化革新提高了建筑项目的效率和质量,并缩短了建筑施工周期。然而,当前建筑信息集成的方式主要基于BIM模型库和关系型数据库,无法实现柔性地基于用户需求的信息组织与传递,极大地增加了信息传递中的承载量,造成系统响应速度慢和效率低下。通过分析建筑工程信息集成与交互的现状,提出基于本体的建筑信息组织与交互模型,并建立建筑信息对本体的映射机制和推理方式。最后以建筑项目运维阶段的管网漏水为实例,分别使用CPN Tools和Jena工具建立本体构架和推理规则,实现漏水区段的定位、关联原因分析及解决方案确认。     

Location determination of mobile devices for an indoor WLAN application using a neural network

Due to the popularity of location-based services, determining the location of a device at all times has become a subject of great interests. Although many GPS-based applications have been developed and successfully deployed in various fields, their applicabilities are hindered by the obstruction of the objects in the environment. Essentially, as satellite signals cannot penetrate the walls of buildings, the coverage of GPS systems is limited to outdoor environments. To fully exploit the benefit of location-based services, approaches that determine the location of a device in indoor environments need to be established. This study presents a novel location determination mechanism that uses an indoor WLAN and back-propagation neural network (BPN). A museum is taken as the context of the example indoor environment. Location determination is achieved using the combined strengths of 802.11b wireless access signals. With a significant number of access points (APs) installed in the museum, hand-held devices can sense the strengths of the signals from all APs to which the devices can connect. Using a back-propagation network, device locations can be estimated with sufficient accuracy. A novel adaptive algorithm is implemented for enhancing the accuracy of the estimation.

支持移动设备接入Gnutella网络的代理架构研究

针对当前移动设备无法加入Gnutella网络实现文件共享网络的现状,提出一种移动代理Gnutella网络架构的设计方案。利用移动代理作为移动设备的代理加入Gnutella网络,帮助移动设备实现文件的共享功能。架构能有效地减少移动设备的信息流量,并支持移动设备在Gnutella网络中实现可移动性。     

A meta-model approach for formal specification and consistent management of multi-LOD building models

The design of a building is a collaborative process among experts from multiple disciplines. Using Building Information Modeling (BIM), a model is developed through multiple refinement stages to satisfy various design and engineering requirements. Such refinements of geometric and semantic information are described as levels of development (LOD). Thus far, there is no method to explicitly define an LOD’s requirements nor to precisely specify the uncertainties involved. Furthermore, despite the insufficient information in the early design stages, a BIM model appears precise and certain, which can lead to false assumptions and model evaluations, for example, in the case of energy efficiency calculations or structural analyses. Hence, this paper presents a multi-LOD meta-model to explicitly describe an LOD’s requirements, incorporating the potential fuzziness of both, geometric and semantic information of individual elements. The explicitly defined fuzziness can be taken into account when applying simulations or analyses for assessing the performance of different building design variants. To support the continuous elaboration of a building from the conceptual to the detailed design stages, the multi-LOD model makes it possible to ensure the consistency of the geometric and semantic information as well as the topological coherence across the different LODs. The feasibility of the approach is demonstrated by its prototypical implementation as a web-server and user-interface, providing a means for managing and checking the exchange requirements both at the meta-level and for concrete building model instances. The paper is concluded with a case study of a real-world construction project that demonstrates the use of the meta-model to support model analysis and the decision-making process.     

Non-visual access to mobile devices: A survey of touchscreen accessibility for users who are visually impaired

Accessibility revolves around building products, including electronic devices and digital content, so that diverse users can conveniently utilize them, irrespective of their capabilities. In recent years, the concept of touchscreen accessibility has gained a remarkable attention, especially within the considerable reliance on mobile touchscreen devices (MTDs) for information acquisition and dissemination as we witness nowadays. For users who are visually impaired, MTDs unlock different opportunities for independence and functioning. Thus, with the increasing ubiquity of MTDs and their potential extensive utility for all demographics, it becomes paramount to ensure that these devices and the content delivered on them are accessible. And while it might seem straightforward to achieve accessibility on MTDs, attaining this outcome is governed by an interplay between different elements. These involve platform (i.e., operating system) built-in support of accessibility features, content rendering modalities and structures pertaining to user needs and the peculiarities of MTDs as informed in standard accessibility guidelines, user studies uncovering preferences and best practices while interacting with MTDs, national legislations and policies, and the use of third-party devices such as assistive technologies. In this paper, mobile touchscreen accessibility for users who are visually impaired is surveyed with focus on three aspects: (1) the existing built-in accessibility features within popular mobile platforms; (2) the nature of non-visual interaction and how users who are visually impaired access, navigate, and create content on MTDs; and (3) the studies that tackled different issues pertaining to touchscreen accessibility, such as extraction of user needs and interaction preferences, identification of most critical accessibility problems encountered on MTDs, integrating mobile accessibility in standard accessibility guidelines, and investigation of existing guidelines in terms of sufficiency and appropriateness.     

Semantic enrichment of building and city information models: A ten-year review

Building Information Models (BIMs) and City Information Models (CIMs) have flourished in building and urban studies independently over the past decade. Semantic enrichment is an indispensable process that adds new semantics such as geometric, non-geometric, and topological information into existing BIMs or CIMs to enable multidisciplinary applications in fields such as construction management, geoinformatics, and urban planning. These two paths are now coming to a juncture for integration and juxtaposition. However, a critical review of the semantic enrichment of BIM and CIM is missing in the literature. This research aims to probe into semantic enrichment by comparing its similarities and differences between BIM and CIM over a ten-year time span. The research methods include establishing a uniform conceptual model, and sourcing and analyzing 44 pertinent cases in the literature. The findings plot the terminologies, methods, scopes, and trends for the semantic enrichment approaches in the two domains. With the increasing availability of data sources, algorithms, and computing power, they cross the border to enter each other’s domain. Future research will likely gain new momentums from the demands of value-added applications, development of remote sensing devices, intelligent data processing algorithms, interoperability between BIM and CIM software platforms, and emerging technologies such as big data analytics.     

Graph-based retrieval of building information models for supporting the early design stages

Building information modeling (BIM) principles are transforming today’s communication and working processes in the field of construction, however the early design phases are only rarely supported and information technology is therefore not exploited to its full potential. The early design phases are characterized by an iterative process of searching for plausible solutions. A common approach is to refer to similar examples, which are conventionally found using keyword-based search strategies.To this end we propose a method for indexing spatial configurations along with a sketch-based input method for search strategies that uses so-called semantic fingerprints of buildings. The topology of spatial configurations is extracted from building information models and represented as graphs. For both building information models and the user sketches, the extracted graphs are used as the basis for a subgraph-matching algorithm facilitating an intuitive novel query method for researching similar reference examples. The system is able to present corresponding existing solutions to even rudimentary sketches or fragments of a design idea. In addition to graph matching and sketch-based interaction, more recent BIM-based approaches are also taken into account.