Automated continuous construction progress monitoring using multiple workplace real time 3D scans

In recent years, exponential growth has been detected in research efforts focused on automated construction progress monitoring. Despite various data acquisition methods and approaches, the success is limited. This paper proposes a new method, where changes are constantly perceived and as-built model continuously updated during the construction process, instead of periodical scanning of the whole building under construction. It turned out that low precision 3D scanning devices, which are closely observing active workplaces, are sufficient for correct identification of the built elements. Such scanning devices are small enough to fit onto workers’ protective helmets and on the applied machinery. In this way, workers capture all workplaces inside and outside of the building in real time and record partial point clouds, their locations, and time stamps. The partial point clouds are then registered and merged into a complete 4D as-built point cloud of a building under construction. Identification of as-designed BIM elements within the 4D as-built point cloud then results in the 4D as-built BIM. Finally, the comparison of the 4D as-built BIM and the 4D as-designed BIM enables identification of the differences between both models and thus the deviations from the time schedule. The differences are reported in virtual real-time, which enables more efficient project management.     

An approach to combine progressively captured point clouds for BIM update

Building information models (BIMs) provide opportunities to serve as an information repository to store and deliver as-built information. Since a building is not always constructed exactly as the design information specifies, there will be discrepancies between a BIM created in the design phase (called as-designed BIM) and the as-built conditions. Point clouds captured by laser scans can be used as a reference to update an as-designed BIM into an as-built BIM (i.e., the BIM that captures the as-built information). Occlusions and construction progress prevent a laser scan performed at a single point in time to capture a complete view of building components. Progressively scanning a building during the construction phase and combining the progressively captured point cloud data together can provide the geometric information missing in the point cloud data captured previously. However, combining all point cloud data will result in large file sizes and might not always guarantee additional building component information. This paper provides the details of an approach developed to help engineers decide on which progressively captured point cloud data to combine in order to get more geometric information and eliminate large file sizes due to redundant point clouds.     

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。     

基于IFC标准的楼层平面尺寸标注自动生成方法研究

在 BIM 协同应用中,二维信息在模型空间布置和构件平面尺寸表达等方面具有重 要作用。由于当前不同专业模型难以集成后统一标注,采用 IFC 标准表达二维信息可有效解决 这一问题。为提高 BIM 构件定位与尺寸的查看效率,提出基于 IFC 标准的二维尺寸标注自动生 成方法。首先研究被标注对象的几何和空间位置信息的提取、分类、转换和存储机制,由此推 导楼层中所有被标注对象的尺寸标注信息。然后研究 IFC 标准中尺寸标注实体的空间定位和形 状表达机制,生成尺寸标注实体并将其关联到被标注对象。最后通过一个两层楼案例,验证该 方法的正确性。     

Towards automatic generation of as-built BIM: 3D building facade modeling and material recognition from images

As-built building information model(BIM) is an urgent need of the architecture, engineering, construction and facilities management(AEC/FM) community. However, its creation procedure is still labor-intensive and far from maturity. Taking advantage of prevalence of digital cameras and the development of advanced computer vision technology, the paper proposes to reconstruct a building facade and recognize its surface materials from images taken from various points of view. These can serve as initial steps towards automatic generation of as-built BIM. Specifically, 3D point clouds are generated from multiple images using structure from motion method and then segmented into planar components, which are further recognized as different structural components through knowledge based reasoning. Windows are detected through a multilayered complementary strategy by combining detection results from every semantic layer. A novel machine learning based 3D material recognition strategy is presented. Binary classifiers are trained through support vector machines. Material type at a given 3D location is predicted by all its corresponding 2D feature points.Experimental results from three existing buildings validate the proposed system.     

Real-time collaborative reconstruction of digital building models with mobile devices

Many software-based building processes require digital building models. Since the building stock does not have sufficient data in this regard, the demand for Scan-to-BIM processes is increasing. In this paper we present a system for the reconstruction of ‘as-built’ BIM content of house interiors based on the Google Tango technology. The strength of our approach is the use of low-cost mobile scanning devices and a client-server system that allows for a real-time collaborative scanning and reconstruction of indoor scenes. We developed a server application that continuously aggregates scan data of multiple scanning devices (clients) and applies the data stream to a real-time post-processing pipeline to reconstruct rooms, walls, doors and windows. The reconstruction result is then distributed to all clients, where it is visualized in real time. The collaborative workflow and real-time data processing make our system especially useful in situations that are time-critical and require concurrent collection and processing of data. One of our targeted use cases therefore is the model generation for crime scene documentation. The effectiveness of our approach was demonstrated on three test sites. Our results compare well to other state-of-art methods regarding the reconstruction of walls, but they also revealed potential for improvement regarding the detection of doors and windows in occluded and cluttered environments.     

基于构件形状分布和配准位置的BIM 模型对比方法

建筑全生命周期的各个阶段中会出现各种不同版本的BIM 模型,其间的差异可以 对建筑的施工和运维阶段提供决策支持。大部分BIM 模型对比都是基于目视检查、手动计数和 选择性属性检查。尽管目前有学者和相关机构研究了一些自动比较BIM 模型的方法,但大多依 赖于模型中构件的ID,而且比较的结果无法直观地体现到具体构件、具体属性上。针对以上问 题,提出了一种基于形状分布和位置配准的BIM 模型对比方法,即提取构件特征进行构件匹配, 从构件级进行BIM 模型对比。首先根据构件的几何信息构造构件的形状分布,计算类型相近构 件的形状分布之间的相似度;再配准构件的位置,计算位置之间的相似度;然后结合2 个相似 度进行构件匹配,比较匹配构件之间的差异;最后得出模型间的差异,并利用WebGL 进行可 视化展示。该方法忽略了构件ID 变化对模型对比的影响,并且能得出模型构件级别的差异。     

基于BIM+CV的现浇混凝土建筑结构构件定位

建筑结构构件定位是自动化进度追踪的关键.现有研究的监控对象均为简单的施工现场,而今建筑的形式越来越复杂且以现浇混凝土结构为主.为了追踪这类建筑的施工进度,基于建筑信息建模(BIM)和计算机视觉(CV)技术,提出了一种从俯视视角对现浇混凝土建筑结构构件定位的方法.首先使用目标检测技术从施工现场俯视图中识别处于施工状态的建...     

Semantic as-built 3D modeling of structural elements of buildings based on local concavity and convexity

The aim of this study is to propose a method for generating as-built BIMs from laser-scan data obtained during the construction phase, particularly during ongoing structural works. The proposed method consists of three steps: region-of-interest detection to distinguish the 3D points that are part of the structural elements to be modeled, scene segmentation to partition the 3D points into meaningful parts comprising different types of elements (e.g., floors, columns, walls, girders, beams, and slabs) using local concave and convex properties between structural elements, and volumetric representation. The proposed method was tested in field experiments by acquiring and processing laser-scan data from construction sites. The performance of the proposed method was evaluated by quantitatively measuring how accurately each of the structural elements was recognized as its functional semantics. Overall, 139 elements of the 141 structural elements (99%) in the two construction sites combined were recognized and modeled according to their actual functional semantics. As the experimental results imply, the proposed method can be used for as-built BIMs without any prior information from as-planned models.     

Towards a unifying domain model of construction safety,health and well-being: SafeConDM

Specific occupational construction safety, health, and well-being related knowledge and information are scattered and fragmented. Despite technological advancements of information and knowledge management, a link between safety management and information models is still missing. In this paper we present first steps towards a unifying formal (logic-based) domain model of construction safety, called SafeConDM, that consists of: (1) a semantically rich ontology of hazard, safety concepts, and concept relationships that builds on, and integrates with, existing construction safety ontologies and building information models; (2) a set of first-order if-then rules linking construction site states with the potential for specific hazards to occur that we define in a novel way using spatial artefacts. We present a prototype software tool, based on our ASP4BIM tool that implements SafeConDM for construction hazard analysis and safe construction planning decision support, and empirically evaluate our tool on three real-world construction building models.     

Ontology based web simulation system for hydrodynamic modeling

Hydrodynamic models generally deal with large sets of data and utilize substantial computational resources. Powerful, robust servers with extensive storage capabilities are desirable for rapid execution. Unfortunately, it is not always possible to effort those kinds of facilities whereas a centralized computer system together with a user access interface can be a viable alternative for many clients. The simplest way a client can communicate with the central simulation server is by a web browser because it is available as a pre-installed application on most every computing platform purchased today. This type of environment is called web based simulation or WBS. In this study, the concepts necessary to design and develop a WBS for the simulation of hydrodynamic processes using legacy (FORTRAN) code are introduced. A formal specification of the simulation domain or an ontology has been developed that is the underlying concept to share, retrieve, and move the simulation data between the different components of the WBS. This ontology can also be used for future analysis and reuse of the simulation domain concepts and the associated data sets.     

基于 AISI 网络的 BIM 三维重建方法研究

自动从点云数据生成建筑信息模型(BIM)一直是建筑自动化领域的研究热点。基于 传统算法的建筑自动三维重建的缺点包括人工设计特征,识别过程复杂,应用场景有限等。随 着三维机器学习领域的不断成熟,处理点云便有了新的手段。通过引入实例分割中的 ASIS 网 络框架对点云进行处理,即从扫描点云场景中自动分割和分类建筑构建元素并得到实例分割矩 阵。接着,基于包围盒假设从得到的实例分割矩阵中提取建筑构件外轮廓参数,并将外轮廓参 数和分割的语义分类结果作为 BIM 建模的构件参数。最后,将这些提取的构件参数输入到自制 的 IFC 生成器中,自动生成基于工业基础类(IFC)标准的 BIM 模型。实验表明,利用无噪点点 云方法,可实现基于曼哈顿世界假设下的室内单房间的三维重建。     

基于智能视觉和BIM的建筑装配过程的高精度控制

为了确保建筑装配过程能实现开发商定义的工业化标准,需要进行建筑装配过程高精度控制。使用当前方法在建筑装配的过程中对建筑装配成本、质量的控制效果达不到开发商的要求;为此,提出一种基于智能视觉和BIM的建筑装配过程高精度控制方法;首先采用BIM技术通过计算机虚拟建筑装配场地布置,建立BIM建筑装配模型,并在BIM建筑装配模型中输入建筑配件以及施工项目相关的所有信息,其次,在BIM建筑装配模型的各个施工构件上加上时间参数和成本计划,构成5D BIM建筑装配模型,对优化完成的5D BIM建筑装配模型进行虚拟建造,调整进度和成本计划,进而将BIM和智能视觉技术相结合,实现整个建筑装配过程的三维可视化指导操作;实验结果表明,所提方法能够有效提高施工效率,且建筑装配成本控制精度较高。     

A digital twin-based approach for the management of geometrical deviations during assembly processes

The recent transformation in the aeronautical industry gives new prospects in the field of product geometry assurance. These include, in particular the creation of sophisticated virtual models, or digital twins, which can reflect the as-built geometry of physical products and optimize the assembly operations consequently. One of the current obstacles to the implementation of such digital twins is linked to the difficult transition from a conceptual model to a usable virtual representation. In this article, we present the hybrid representation of a product which is capable of integrating the different states of the components at each step of the assembly process. We propose a method to update the virtual representation of already assembled components, in order to include the position and orientation deviations of their surfaces. The B-Rep model of each component is updated from data acquired during the assembly of the product. The various steps of this update, and its associated tools are discussed in the article. Based on the knowledge of the as-built component geometry, the geometry of the yet-to-be-assembled components is adapted so that the final product complies with the functional requirements. To this end, we also discuss a formalism to model the product's functional information and to translate it at a geometrical level thanks to an assembly skeleton.     

BIM技术在珠三角水资源配置工程中的集成应用

针对水利工程行业数字化、信息化、智慧化水平较低,生产管理手段较落后问题,基于珠江三角洲水资源配置工程探索研究施工阶段BIM技术的集成应用,以BIM技术为基础,结合其他数字化与信息技术,搭建基于BIM技术的多维度数据管理支撑平台,从态势分析与辅助决策(进度、质量、安全、资金)、基于BIM+GIS的专题应用(盾构机与TBM设备状态跟踪与高效运行可视化应用场景、地下工程与地面设施影响监控保障可视化应用场景、地面场景720全景图像虚拟现实呈现、VR/AR培训体验)两大方面为切入点进行深度应用,将BIM+GIS模型与工程建设管理要素相结合,实现精确、可视化的工程管理,提高工程管理的精细化程度和业务决策效率。这一应用经验也标志着数字化技术正颠覆着原先的传统工程建管模式,积极推动数字化转型。     

面向Web信息资源的领域本体模型自动构建机制的研究

领域本体的构建是本体工程研究与应用的重要内容。面向网络Web信息资源,获取领域相关文本信息,通过对文本的概念分析,构建领域本体模型。提出一套本体自动构建机制,该本体构建基于数据挖掘和机器学习技术,内容主要包括基于贝叶斯(Bayes)分类原理;提出多个分类器方式的概念分类过程和算法;提出概念关联分析和概念自学习算法,建立本体原型;提出面向OWL本体模型的转换映射机制,构建基于OWL的本体模型。此外,还提出了从网络资源获取、领域本体建模到本体实施应用的一套完整的本体构建和应用实施的解决方案。     

Smart Vidente: advances in mobile augmented reality for interactive visualization of underground infrastructure

Many civil engineering tasks require to access geospatial data in the field and reference the stored information to the real-world situation. Augmented reality (AR), which interactively overlays 3D graphical content directly over a view of the world, can be a useful tool to visualize but also create, edit and update geospatial data representing real-world artifacts. We present research results on the next-generation field information system for companies relying on geospatial data, providing mobile workforces with capabilities for on-site inspection and planning, data capture and as-built surveying. To achieve this aim, we used mobile AR technology for on-site surveying of geometric and semantic attributes of geospatial 3D models on the user’s handheld device. The interactive 3D visualizations automatically generated from production databases provide immediate visual feedback for many tasks and lead to a round-trip workflow where planned data are used as a basis for as-built surveying through manipulation of the planned data. Classically, surveying of geospatial objects is a typical scenario performed from utility companies on a daily basis. We demonstrate a mobile AR system that is capable of these operations and present first field trials with expert end users from utility companies. Our initial results show that the workflows of planning and surveying of geospatial objects benefit from our AR approach.     

Information modeling of earthquake-damaged reinforced concrete structures

Accurate and reliable information about buildings can greatly improve post-earthquake responses, such as search and rescue, repair and recovery. Building Information Modeling (BIM), rapid scanning and other assessment technologies offer the opportunity not only to retrieve as-built information but also to compile as-damaged models. This research proposes an information model to facilitate the data flow for post-earthquake assessment of reinforced concrete structures. The schema development was based on typical damage modes and the existing Industry Foundation Class (IFC) schema. Two examples of damaged structures from recent earthquake events, compiled using an experimental damage modeling software, illustrate the use of the data model. The model introduces two new classes, one to represent segments of building elements and the other to model the relationships between segments and cracks. A unique feature is the ability to model the process of damage with a binary tree structure. Methods for exporting as-damaged instance models using IFC are also discussed.     

Registration of technical drawings and calibrated images for industrial augmented reality

Despite tremendous progress in 3D modelling technology, most sites in traditional industries do not have a computer model of their facilities at their disposal. In these industries, 2D technical drawings are typically the most commonly used documents. In many cases, a database of fully calibrated and oriented photogrammetric images of parts of the plant is also available. These images are often used for metric measurement and 3D as-built modelling. For planning revamps and maintenance, it is necessary to use industrial drawings as well as images and 3D models represented in a common “world” coordinate system. This paper proposes a method for full integration of technical drawings, calibrated images and as-built 3D models. A new algorithm is developed in order to use only a few correspondences between points on a technical drawing and multiple images to estimate a metric planar transformation between the drawing and the world coordinate system. The paper describes the mathematical relationship between this transformation and the set of homographies needed for merging the technical drawing with all the calibrated images. The method is implemented and fully integrated into an industrial software we developed for 3D as-built reconstruction. We present examples of a real application, in which the method is successfully applied to create an augmented reality representation of a waste water plant. Accepted: 13 August 2001     

Querying a building information model for construction-specific spatial information

The design and construction community has shown increasing interest in adopting building information models (BIMs). The richness of information provided by BIMs has the potential to streamline the design and construction processes by enabling enhanced communication, coordination, automation and analysis. However, there are many challenges in extracting construction-specific information out of BIMs. In most cases, construction practitioners have to manually identify the required information, which is inefficient and prone to error, particularly for complex, large-scale projects. This paper describes the process and methods we have formalized to partially automate the extraction and querying of construction-specific information from a BIM. We describe methods for analyzing a BIM to query for spatial information that is relevant for construction practitioners, and that is typically represented implicitly in a BIM. Our approach integrates ifcXML data and other spatial data to develop a richer model for construction users. We employ custom 2D topological XQuery predicates to answer a variety of spatial queries. The validation results demonstrate that this approach provides a richer representation of construction-specific information compared to existing BIM tools.