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.     

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.     

NIST Research toward Construction Site Integration and Automation

Current uses of computers in construction include design, planning, scheduling, and cost estimating. Much more could be achieved on a fully computer-integrated construction site. This paper describes initial work at the National Institute of Standards and Technology toward construction site integration and automation, beginning with a simple steel-erection procedure using an instrumented crane. CAD-generated geometry sets are transformed into a library of 3D construction site objects. These objects are then loaded into an augmented simulation system that tracks both equipment and resources based on real-time data from the construction site. With some future enhancements, the end result will be a world model of the site, in which as-built conditions can be assessed, current construction processes can be viewed as they occur, planned sequences of processes can be tested, and object information can be retrieved on demand. A project can be viewed and managed remotely using this tool. Remotely controlled construction in hazardous environments is a natural extension of this environment. The National Construction Automation Testbed (NCAT) is currently being used in various research projects with the intentions of making such possibilities a reality. A major effort in the NCAT is the development and testing of the metrology, communication, and simulation protocols required.     

Real-Time Three-Dimensional Occupancy Grid Modeling for the Detection and Tracking of Construction Resources

Awareness of the construction environment can be improved by automatic three-dimensional (3D) sensing and modeling of job sites in real time. Commercially available 3D modeling approaches based on range scanning techniques are capable of modeling static objects only, and thus cannot model dynamic objects in real time in an environment comprised of moving humans, equipment, and materials. Emerging prototype video range cameras offer an alternative by facilitating affordable, wide field of view, dynamic object tracking at frame rates better than 1?Hz (real time). This paper describes a methodology to model, detect, and track the position of static and moving objects in real time, based on data obtained from video range cameras. Experiments with this technology have produced results that indicate that video rate 3D data acquisition and analysis of construction environments can support effective modeling, detection, and tracking of project resources. This approach to job site awareness has inherent value and broad application. In combination with effective management practices and other sensing techniques, this technology has the potential to significantly improve safety on construction job sites.     

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.     

Frames of Reference in Mobile Augmented Reality Displays.

In 3 experiments, the authors investigated spatial updating in augmented reality environments. Participants learned locations of virtual objects on the physical floor. They were turned to appropriate facing directions while blindfolded before making pointing judgments (e.g., "Imagine you are facing X. Point to Y"). Experiments manipulated the angular difference between the learning heading and the imagined heading and between the actual heading and the imagined heading. The effect of actual-imagined on pointing latency was observed for naive users but not for users with brief training or instructions concerning the fact that objects can move with body movements. The results indicated that naive users used an environment-stabilized reference frame to access information arrays, but with experience and instruction the nature of the representation changed from an environment stabilized to a body stabilized reference frame. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of Augmented Reality for Rapid Assessment of Earthquake-Induced Building Damage

This paper discusses the feasibility of using augmented reality (AR) to evaluate earthquake-induced building damage. In the proposed approach, previously stored building information is superimposed onto a real structure in AR. Structural damage can then be quantified by measuring and interpreting key differences between the real and augmented views of the facility. Proof-of-concept experiments were performed in conjunction with large-scale cyclic shear wall tests. In these, CAD images of the walls were superimposed onto the wall specimens. Then, as the wall specimens were deformed under applied loading, the horizontal drifts between the walls and the augmented images were computed using two different techniques and compared with actual wall drifts. The obtained results highlight the potential of using AR for rapid damage detection and indicate that the accuracy of structural displacements measured using AR is a direct function of the accuracy with which augmented images can be registered with the real world. The limitations of the technology, considerations for field implementation, and the potential for other related applications of AR are also discussed.     

Object Recognition in Construction-Site Images Using 3D CAD-Based Filtering

Construction-site images that are now easily obtained from digital cameras have the potential to automatically provide the project status information. For example, once construction objects such as concrete columns are accurately identified and counted, the current level of project progress in the column installation activity can easily be measured. However, in order to identify and count the number of concrete columns installed at a particular point of time, a robust object recognition methodology is required. Without the successful recognition and extraction of the construction object of interest, it is almost impossible to understand the current level of project progress. This paper presents a robust image processing methodology to effectively extract the objects of interest from construction-site digital images. The proposed methodology makes use of advanced imaging algorithms and a three-dimensional computer aided design perspective view to increase the accuracy of the object recognition. Tests show that the methodology is promising and expected to provide a solid base for the successful, automatic acquisition of project information.     

VR技术在矿工安全培训中的应用研究

传统的矿工培训高成本、低效益,不能适应井下复杂多变特殊环境的要求。本文应用计算机技术,采用基于虚拟现实的方法,构建了井下生产的虚拟环境;在这个虚拟环境中,矿工可以身临其境地去接触、认知、决策和处理各种突变情况,其决策结果会立即反馈给受训者,由此提高矿工的培训效果。     

Time out of mind: Dissociation in the virtual world.

While greatly facilitating ease of interaction across time and geographic boundaries, the virtual world presents an unreal universe comprised of instant connection and gratification. Our culture has embraced this alternate reality in the form of online journals, chat rooms, and excessive involvement with video games, as well as Internet pornography and sexual solicitation. Psychoanalytic principles can greatly illuminate our understanding of individuals' involvement with virtual reality as it becomes disruptive to work and meaningful relationships. Two cases will be used to illustrate overinvolvement with the virtual world as a form of dissociation in which the individuals retreat from the painful memories, deficits, and helplessness they experience in the real world to a subjective state in which they can attempt to exercise control and aggressively capture the supplies they lack. In the course of treatment, the dissociated material must be invited into the therapeutic dyad so that it may become a conscious and accepted part of the self. The process involves both verbal interpretation and relational grounding in the person of the therapist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

对虚拟货币交易征税的法律探讨

虚拟货币的特殊性使得对虚拟货币交易进行征税存在颇多争议。但交易者通过虚拟货币交易却实现了真实的财产收益,这使得虚拟货币交易符合税收征收对象的基本要件。加强对虚拟货币交易征税的可行性和必要性研究,修订并完善税收法律法规,对于加强政府对虚拟货币交易的宏观调控,具有现实意义。     

Infrastructure of Partnering for Construction Projects

This paper highlights the importance of establishing an infrastructure for partnering. First, a structure of partnering is suggested. The structure represents the ability to develop and disseminate resources that can be shared among involved parties in the partnering organization. Second, an infrastructure of partnering is described. It has some core functions, such as receiving, storing, retrieving, coding, etc., and supports the running of partnering in a real environment as well as a virtual environment. Workshops are essential for face-to-face contacts in a real environment while computerization helps to facilitate interaction between parties in a virtual environment. Also, a computer-based network terminal and a codification system are presented. Finally, two cases are presented to illustrate the current practices of construction partnering and justify the functions of the infrastructure. Some practical implications are provided to make the infrastructure more available to the construction industry.     

Removal of Redundant Relationships in an AON Project Network for Evaluating Schedule Complexity

Since redundant relationships in an activity-on-node (AON) project network indicate that the schedule is more complex than it actually is, they should not be considered when evaluating the schedule complexity. However, identifying the relationships that can be removed while maintaining the project logic is not an easy task. For this purpose, this paper proposes a methodology, adapted from interpretive structural modeling, that basically transforms an AON project network into a network called minimum-edge diagraph which contains no redundant relationships. The methodology steps are explained through a demonstrative example of a simple hypothetical project. The application of the methodology to the AON network of a real construction project shows that it is easy to use yet effective in removing redundant relationships.     

Application of a Virtual Environment System in Building Sciences Education

This paper includes a brief review of the application of virtual environments in building sciences and presents details of the application of virtual structural analysis program (VSAP), a virtual reality based structural analysis system developed at Virginia Polytechnic Institute and State Univ. (Virginia Tech), in education and practice. Different elements and modeling options in addition to the implementation of two major earthquakes within VSAP for the demonstration of the behavior of building structures during seismic activities are presented. Modifications to the VSAP in order to simulate progressive collapse of building structures are discussed. Different versions of this system were used in architectural structures courses at Virginia Tech. Results of feedbacks from students in these classes are presented. From these results it is concluded that the VSAP can be used effectively as an experiential teaching∕learning tool in classroom settings. Possible applications of VSAP as a design and research tool in construction industry are discussed.     

Creative expression in virtual worlds: Imitation, imagination, and individualized collaboration.

Internet use has increased dramatically in the past two decades, including the use of three-dimensional virtual environments in which individuals represent themselves via avatars and can develop and share creative content within those worlds. The authors examine the content of virtual worlds with particular attention to tools that allow expressing individuality, objects that appear to imitate real world content, as well as those that break from real world constraints. The authors also introduce the construct of individualized collaboration. Unlike face-to-face group activities in real world settings, in which the ambient conditions are largely the same for all participants, virtual worlds have properties that make it possible, in principle, for individuals to personalize their experience even while interacting with others in collaborative groups. Virtual worlds provide an opportunity to ask traditional questions about creativity in a new context, but also introduce a range of new questions that can lead to new insights and understandings about creativity in general. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automated Generation of Operations Level Construction Animations in Outdoor Augmented Reality

Three-dimensional (3D) visualization is an effective tool for communicating, verifying, and validating the results of a simulated operation. Traditional visualization tools used for this purpose are typically based on the paradigm of virtual reality. Augmented reality (AR) is a relatively newer visualization paradigm whose engineering applications have been explored by a limited number of researchers. In this paper, the problem of generating smooth and continuous AR animations from the results of running discrete event simulation models and a general purpose methodology to overcome this challenge are discussed. The structure of an AR animation authoring language developed by the writers to create a logical link between a running simulation model and its corresponding 3D visualization in AR is described. In order to validate the functionality and effectiveness of the designed methods and animation language, an AR-based visualization application was developed and the designed algorithms were successfully tested using different simulation scenarios of varying visual and operational complexity.     

Comparison of Using Mixed-Integer Programming and Genetic Algorithms for Construction Site Facility Layout Planning

The use of modular construction has gained wide acceptance in the industry. For a specific construction facility layout problem such as site precast standardized modular units, it requires the establishment of an on-site precast yard. Arranging the precast facilities within a construction site presents real challenge to site management. This complex task is further augmented with the involvement of several resources and different transport costs. A genetic algorithm (GA) model was developed for the search of a near-optimal layout solution. Another approach using mixed-integer programming (MIP) has been developed to generate optimal facility layout. These two approaches are applied to solve with an example in this paper to demonstrate that the solution quality of MIP outperforms that of GA. Further, another scenario with additional location constraints can also be solved readily by MIP, which, however, if modeled by GA, the solution process would be complicated. The study has highlighted that MIP can perform better than GA in site facility layout problems in which the site facilities and locations can be represented by a set of integer variables.     

Influence of transducer frequency on Doppler microemboli signals in an in vivo model

The purpose of this study was to apply virtual reality technology to spiral computed tomographic (CT) angiogram images in a rabbit model of atherosclerosis and to correlate the images with histopathologic evaluation of the aorta. Image data were transferred to the virtual endoscope system in a graphics workstation. "Virtualized angioscopy" includes an interactive graphic user interface, which controls the viewpoint, the direction of the observation, and rendering and navigation functions. The virtual angioscopy system demonstrated irregularities of the luminal surface of the ascending aorta and a smooth luminal surface in the descending aorta. These observations were correlated with histopathologic findings. The results of this study indicate that the potential and real benefits of virtualized angioscopy far outweigh several technical limitations.     

Analytical Approach to Augmenting Site Photos with 3D Graphics of Underground Infrastructure in Construction Engineering Applications

This paper proposes an analytical approach to incorporating computer-generated three-dimensional (3D) graphics of invisible underground infrastructure into site photos so as to present a richer and more integral view of the site situation in construction engineering applications. The proposed approach simulates the image-forming process of a camera and produces a virtual photo of the underground scene, whose virtual coordinate axes coincide with the real coordinate axes of the aboveground site scene. As a result, the virtual photo and the site photo can be seamlessly merged in terms of perspective, position, and scale. This research simplifies the calculation of the camera’s spatial orientation by use of only two reference points’ positions, i.e., the camera station position and the object focus position. The whole procedure of the proposed approach is analytical and can be automated into a computer program. In practice, nondestructive subsurface imaging technologies are generally used to obtain the spatial data of the underground infrastructure, which can be readily processed into a 3D as-built model as one component in composing the virtual underground scene. The proposed approach is demonstrated with a case study in which the underground as-built data are superimposed onto the aboveground site photo for the purpose of quality investigation of a bored pile construction.     

基于可视化虚拟现实技术的炼钢—连铸生产调度系统

采用虚拟现实技术开发了钢铁企业炼钢－连铸调度计划的调度系统。此方法利用虚拟现实技术的反馈设计和可视化的特点,能够使计划编制人员方便而有铲地制定调度计划。提出的调度方法有界面友好、结论直观、模型修改方便等优点。