Georeferenced Registration of Construction Graphics in Mobile Outdoor Augmented Reality

This paper describes research that investigated the application of the global positioning system and 3 degree-of-freedom (3-DOF) angular tracking to address the registration problem during interactive visualization of construction graphics in outdoor augmented reality (AR) environments. The global position and the three-dimensional (3D) orientation of a user’s viewpoint are tracked, and this information is reconciled with the known global position and orientation of superimposed computer-aided design (CAD) objects. Based on this computation, the relative translation and axial rotations between the user’s viewpoint and the CAD objects are continually calculated. The relative geometric transformations are then applied to the CAD objects inside a virtual viewing frustum that is coincided with the real world space that is in the user’s view. The result is an augmented outdoor environment where superimposed graphical objects stay fixed to their real world locations as the user navigates. The algorithms are implemented in a software tool called UM-AR-GPS-ROVER that is capable of interactively placing static and dynamic 3D models at any location in outdoor augmented space. The concept and prototype are demonstrated with an example in which scheduled construction activities for the erection of a structural steel frame are graphically simulated in outdoor AR.     

Automated Recognition of 3D CAD Objects in Site Laser Scans for Project 3D Status Visualization and Performance Control

This paper presents a new approach that allows automated recognition of three-dimensional (3D) computer-aided design (CAD) objects from 3D site laser scans. This approach provides a robust and efficient means to recognize objects in a scene by integrating planning technologies, such as multidimensional CAD modeling, and field technologies, such as 3D laser scanning. Using such an approach, it would be possible to visualize the 3D status of a project and automate some tasks related to project control. These tasks include 3D progress tracking, productivity tracking, and construction dimensional quality assessment and quality control. This paper provides an overview of the developed approach and demonstrates its performance in object recognition and project 3D status visualization, with data collected from a construction job site.     

Human-Assisted Obstacle Avoidance System Using 3D Workspace Modeling for Construction Equipment Operation

Equipment operation on construction sites is a major source of construction accidents and injuries related to crushing, electrocution, and falls. Primarily, this is because the operator’s field of view, reaction speed, attention, and depth perception are limited, and also because the construction site is a dynamic environment. Accelerating advances in sensing and equipment control sophistication present new opportunities to address these safety problems. The research described here provides the basis for the development of obstacle-avoidance systems that use models of objects generated by rapid three-dimensional (3D) workspace modeling methods and by sophisticated equipment control capabilities. An explanation of the proposed obstacle avoidance system, together with preliminary results, is presented. Implementation of this system in practice is feasible in the near term for critical and particularly hazardous operations.     

复杂环境下一种基于SiamMask的时空预测移动目标跟踪算法

随着无人工厂、智能安监等技术在制造业领域的深入应用,以视觉识别预警系统为代表的复杂环境下动态识别技术成为智能工业领域的重要研究内容之一。在本文所述的工业级视觉识别预警系统中,操作人员头发区域由于其具有移动形态非规则性、运动无规律性的特点,在动态图像中的实时分割较为困难。针对此问题,提出一种基于SiamMask模型的时空预测移动目标跟踪算法。该算法将基于PyTorch深度学习框架的SiamMask单目标跟踪算法与ROI检测及STC时空上下文预测算法相融合,根据目标时空关系的在线学习,预测新的目标位置并对SiamMask模型进行算法校正,实现视频序列中的目标快速识别。实验结果表明,所提出的算法能够克服环境干扰、目标遮挡对跟踪效果的影响,将目标跟踪误识别率降低至0.156%。该算法计算时间成本为每秒30帧,比改进前的SiamMask模型帧率每秒提高3.2帧,算法效率提高11.94%。该算法达到视觉识别预警系统准确性、实时性的要求,对移动目标识别算法模型的复杂环境应用具有借鉴意义。      

Benefits and Barriers of Construction Project Monitoring Using High-Resolution Automated Cameras

A more rapid and widespread use and implementation of technology in construction often fails since its benefits and limitations remain somewhat unclear. Project control is one of the most variable and time consuming task of construction project managers and superintendents and yet continues to be mostly a manual task. Controlling tasks such as tracking and updating project schedules can be assisted through remotely operating technology such as high-resolution cameras that can provide construction management and other users with imaging feeds of job site activities. Although construction cameras have been around for many years, the costs, benefits, and barriers of their use have not been investigated nor quantified in detail. Subsequently, definitions and understanding vary widely, making it difficult for decision makers at the organizational level to decide on the investment in camera technology. This paper reviews the status of high-resolution cameras and their present use in construction. Results of a multiphased survey to industry professionals were collected in order to identify benefits and barriers and develop a cost-benefit model that can be used for implementation technology in construction.     

Distributed Augmented Reality for Visualizing Collaborative Construction Tasks

Augmented reality is a visualization method in which virtual objects are aligned with the real world and the viewer can interact with the virtual objects in real time. In this paper, a new methodology called distributed augmented reality for visualizing collaborative construction tasks (DARCC) is proposed. Using this methodology, virtual models of construction equipment can be operated and viewed by several operators to interactively simulate construction activities on the construction site in augmented reality mode. The paper investigates the design issues of DARCC including tracking and registration, object modeling, engineering constraints, and interaction and communication methods. The DARCC methodology is implemented in a prototype system and tested in a case study about a bridge deck rehabilitation project.     

曹妃甸项目倾斜摄影生成三维模型的实践总结

近年来倾斜摄影的飞速发展,三维实景建模技术也日趋成熟。通过简单的操作就可以得到真实三维模型,这项技术被越来越多的应用于项目中。本文曹妃甸项目为例,从影像数据采集方法、实景建模流程、实景模型数据应用方向进行阐述三维实景建模技术的工作流程。     

Building Integrated Architecture/Engineering/Construction Systems Using Smart Objects: Methodology and Implementation

Integrated project systems hold the promise for improving the quality while reducing the time and cost of architecture/engineering/construction (AEC) projects. A fundamental requirement of such systems is to support the modeling and management of the design and construction information and to allow the exchange of such information among different project disciplines in an effective and efficient manner. This paper presents a methodology to implement integrated project systems through the use of a model-based approach that involves developing integrated “smart AEC objects.” Smart AEC objects are an evolutionary step that builds upon past research and experience in AEC product modeling, geometric modeling, intelligent CAD systems, and knowledge-based design methods. Smart objects are 3D parametric entities that combine the capability to represent various aspects of project information required to support multidisciplinary views of the objects, and the capability to encapsulate “intelligence” by representing behavioral aspects, design constraints, and life-cycle data management features into the objects. An example implementation of smart objects to support integrated design of falsework systems is presented. The paper also discusses the requirements for extending existing standard data models, specifically the Industry Foundation Classes (IFC), to support the modeling of smart AEC objects.     

Ubiquitous Sensor Network for Construction Material Monitoring

Timely acquisition of construction resource information is an essential task for construction engineers and managers. Due to the harsh and dynamic construction environment, it is not easy to acquire construction information in real time. This paper presents a radio frequency identification (RFID) and ZigBee (IEEE 802.15.4)-based system to manage materials on a busy construction site where a data communications system is not in place. RFID tags are attached to and used to identify various kinds of construction materials, and the ZigBee communication technology is used to wirelessly transfer this information. To confirm the viability of our system, the RFID and ZigBee technologies were assessed using an indoor experiment. Following this, a field experiment was then conducted. On a building construction site, a range of construction materials was identified using RFID tags and this information was transferred to an end user with the help of ZigBee multihop networking. The results of the field experiment showed an acceptable reading range and rate for the proposed system. Therefore, the integrated system with RFID and ZigBee modules demonstrated great potential for improving the existing management processes for construction resources on large and complex construction sites.     

Linear Scheduling Using Optimal Control Theory

Construction planning and control literature reveal much effort in the recent past in the development of managerial control systems involving classical optimization techniques such as simulation, queuing theory, linear, dynamic programming, etc. Construction managers typically reach decisions in a perspective of time and in light of temporal criteria. The aforementioned techniques deal with the theoretical and computational aspects of time by static methods: Effects of one or more actions in a given interval are aggregated over time. Optimal Control Theory, a new branch of optimization, makes it possible to view the construction‐production process as a dynamic system that evolves over time. This paper presents a Continuous Optimal Control formulation of a hypothetical cut‐and‐fill job on a section of a highway. It is shown that Discrete Optimal Control framework is adequate for construction. The problem of scheduling the construction of a bridge due to Selinger is solved using this approach.     

Sensing and Field Data Capture for Construction and Facility Operations

Collection of accurate, complete, and reliable field data is not only essential for active management of construction projects involving various tasks, such as material tracking, progress monitoring, and quality assurance, but also for facility and infrastructure management during the service lives of facilities and infrastructure systems. Limitations of current manual data collection approaches in terms of speed, completeness, and accuracy render these approaches ineffective for decision support in highly dynamic environments, such as construction and facility operations. Hence, a need exists to leverage the advancements in automated field data capture technologies to support decisions during construction and facility operations. These technologies can be used not only for acquiring data about the various operations being carried out at construction and facility sites but also for gathering information about the context surrounding these operations and monitoring the workflow of activities during these operations. With this, it is possible for project and facility managers to better understand the effect of environmental conditions on construction and facility operations and also to identify inefficient processes in these operations. This paper presents an overview of the various applications of automated field data capture technologies in construction and facility fieldwork. These technologies include image capture technologies, such as laser scanners and video cameras; automated identification technologies, such as barcodes and Radio Frequency Identification (RFID) tags; tracking technologies, such as Global Positioning System (GPS) and wireless local area network (LAN); and process monitoring technologies, such as on-board instruments (OBI). The authors observe that although applications exist for capturing construction and facility fieldwork data, these technologies have been underutilized for capturing the context at the fieldwork sites as well as for monitoring the workflow of construction and facility operations.     

无人机三维实景建模技术在矿山地质信息提取中的应用研究

由于科学技术的发展和地质勘查工作的需要,地质找矿工作面临着一定的技术难题,发现在成矿空间内无法准确提取到成矿信息,为了更好地探明矿山深部及外围地质情况,在地质勘查工作中运用无人机三维实景建模技术提取矿山地质信息,建立三维矿山地质模型,可以更加真实的展示矿山的三维空间形态,依照地质学原理,利用无人机三维实景建模技术可以去除无人机航拍图像中的干扰项,实验结果表明,该方法信息提取精度较高,可以为地质找矿及矿产资源动态监测工作提供重要的理论依据。     

Use of Stereoscopy for Dam Break Flow Measurement

This investigation explored the applicability of video stereoscopy for the measurement of unsteady open channel flows. Specifically, the three-dimensional water surface profile and flow velocities associated with scale model dam break events were considered. Stereo images of the unsteady flow event were obtained using three, time-synchronized, video cameras situated above the tank such that, at all times, the area of interest was captured by at least two of the three cameras. To establish a point of reference from image to image, floating plastic tracking particles were placed on the water surface. The three-dimensional coordinates of the particles were then calculated using the camera positions and the locations of the individual plastic particles in the stereo images. Particle velocities were also deduced from the analysis of consecutive images. Based on this preliminary investigation we conclude that video stereoscopy is a promising method for measuring highly dynamic flows.     

Use of Tangible and Augmented Reality Models in Engineering Graphics Courses

Engineering graphics courses are typically a requirement for engineering students around the world. Besides understanding and depicting graphic representation of engineering objects, the goal of these courses is to provide students with an understanding of the relationship between three-dimensional (3D) objects and their projections. However, in the classroom, where time is limited, it is very difficult to explain 3D geometry using only drawings on paper or at the blackboard. The research presented herein aims to develop two teaching aids; a tangible model and an augmented reality (AR) model, to help students better understand the relationship between 3D objects and their projections. Tangible models refer to the physical objects which are comprised of a set of differently shaped pieces. The tangible model we developed includes eight wooden blocks that include all the main geometrical features with respect to their 3D projections. The AR models are the virtual models which can superimpose 3D graphics of typical geometries on real-time video and dynamically vary view perspective in real-time to be seen as real objects. The AR model was developed using the ARToolKitPlus library and includes all the geometrical features generally taught in engineering graphics courses or technical drawing courses. To verify the effectiveness and applicability of the models we developed, we conducted a user test on 35 engineering-major students. The statistical results indicated that the tangible model significantly increased the learning performance of students in their abilities to transfer 3D objects onto two-dimensional (2D) projections. Students also demonstrated higher engagement with the AR model during the learning process. Compared to using the screen-based orthogonal and pictorial images, the tangible model and augmented reality model were evaluated to be more effective teaching aids for engineering graphics courses.     

Using Global Positioning System to Improve Materials-Locating Processes on Industrial Projects

On-site materials-handling operations are error prone and the errors that occur significantly decrease construction productivity. New technologies and sensing devices can enhance materials-handling management practices on construction job sites. This paper describes a study that aimed to determine the potential benefits of the deployment of global positioning system (GPS) technology within the materials-locating processes on industrial projects. Its main goals were (1) to evaluate the technical feasibility and (2) to quantify the direct benefits in terms of process duration derived from the integration of GPS devices within pipe-locating processes. A field trial was conducted and its results indicated significant time savings. This study also analyzed additional potential benefits derived from the use of GPS in this scenario.     

Imaging input technology

Imaging input technology is at its greatest rate of development ever, with CCD technology improving both in terms of image quality and image economy. The current diversity of imager modalities and application specializations allows for elegant matching of device capability to image subject photographic requirements. Both color and low-light imaging technologies continue to evolve, with ever-increasing resolution and dynamic range. The "order of magnitude" cost decreases that so aptly characterized the computer industry of the 1970s and 1980s is now upon the digital imager industry. Although analog cameras, based on video formats, still prevail, the direct digital camera will emerge as the preferred input device within a decade.     

Modeling and Visualization of Underground Structures

Based on the solid modeling, transformation operation and Boolean operation techniques widely available in computer-aided design and drafting system, first, this paper proposed a general modeling method for dynamic underground structure simulation. Then, representations of underground structures, ground, and related information in three-dimensional space were investigated. Some suggestions were put forwarded to improve visualization results, including object organization by layers, thematic viewing, level of detail for object representation, and spatial cueing for useful information. Application examples were given to illustrate the visualization effects. Finally, virtual reality technology was employed in the simulation of the underground structures. By positioning objects using real-time information, picking objects, and then accessing their real world working status through the Internet, the realistic results of a virtual system were further discussed. It has also been found that in order to obtain satisfactory visual results using an inexpensive desktop computer, a virtual reality model must be optimized from the perspective of reducing object complexity as well as efficient scene management.     

Algorithm of Crane Selection for Heavy Lifts

Lifting capacity charts are tabulated and provided to operators and practitioners by mobile crane manufacturers. These charts are structured based on predetermined crane configurations, which consist of boom/jib length, lifting radius, main boom angle to ground, and jib angle to ground or its offset to its main boom centerline. It is a tedious job that lifting planners select cranes for construction projects based on a large number of lifting capacity charts. This paper presents a newly developed algorithm for selecting mobile cranes on construction sites, which takes into account the lifting capacity, the geometrical characteristics of the crane, the dimensions of equipments and riggings, and the ground bearing pressure. The algorithm is incorporated into a three-dimensional (3D) computer-aided system that integrates crane selection module, crane modeling module, 3D-simulation module, 3D computer-aided design modeling module, rigging calculation module, and data management module. At last, a case is represented in order to demonstrate the use of the developed algorithm and to illustrate its essential features.     

Computer Vision-Based Video Interpretation Model for Automated Productivity Analysis of Construction Operations

Videotaping is an effective and inexpensive technique that has long been used in construction to conduct productivity analyzes. However, as schedules of modern construction projects become more and more compressed, the limitation of video-based analysis—intensive manual reviewing process—contrasts sharply with the need for effortless data analysis methods. This paper presents a study on developing a video interpretation model to interpret videos of construction operations automatically into productivity information. More specifically, this research formalizes key concepts and procedures of video interpretation within the construction domain. It focuses on designing a mechanism for furthering the crosstalk between the prior knowledge of construction operations and computer vision techniques. It uses this mechanism to guide the detection and tracking of project resources as well as work state classifications and abnormal production scenario identifications. The resulting approach has the potential to provide a common base for developing automated video interpretation procedures that can greatly improve current data collection and analyzes practices in construction. Experimental results from preliminary studies have shown the potential of the proposed video interpretation method as an improved productivity data analysis method.     

The role of visual working memory in attentive tracking of unique objects.

When tracking moving objects in space humans usually attend to the objects’ spatial locations and update this information over time. To what extent do surface features assist attentive tracking? In this study we asked participants to track identical or uniquely colored objects. Tracking was enhanced when objects were unique in color. The benefit was greater when the distance between distractors and targets was smaller, but was eliminated when the objects changed colors 1 to 4 times per second, even though at any instant they were always uniquely colored. In addition, tracking uniquely colored objects impaired a secondary color-memory task more than tracking identical objects, and holding several colors in working memory eliminated the advantage of tracking uniquely colored objects. Contrary to previous studies showing that feature information is poorly retained during tracking, these findings indicate that surface properties are stored in visual working memory to facilitate tracking performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)