A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads t...A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.展开更多
The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation ...The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation algorithm is proposed based on the geometric analysis and the angular propagation （AP）, and a 3-D real-time interactive system is developed for the motion simulation of the guide wire and the catheter inside the specific patient vascular. The guide wire or the catheter is modeled as the ＂multi-body＂ representation and properties are defined by its intrinsic characteristics. The motion of the guide wire or the catheter inside the vascular is guided by the collision detection and the collision cancellation algorithm. Finally, a relaxation procedure is used to achieve more realistic status. Experimental results show that the behavior of the guide wire or the catheter depends on the defined parameters. The real-time simulation can be achieved. The result shows that the simulation system is effective and promising.展开更多
Virtual reality(VR) training technology in the mining industry is a new field of research and utilization.The successful application of VR training system is critical to mine safety and production. Through the statist...Virtual reality(VR) training technology in the mining industry is a new field of research and utilization.The successful application of VR training system is critical to mine safety and production. Through the statistics of the current research and applications of VR training systems in mining industry, all the input/output devices are classified. Based on the classifications of the input/output devices that are used in the VR system, the current VR training systems for the mining industry could be divided into three types: screen-based general type, projector-based customized type, and head-mounted display(HMD)-based intuitive type. By employing a VR headset, a smartphone and a leap motion device, an HMDbased intuitive type VR training system prototype for drilling in underground mines has been developed.Ten trainees tried both the HMD-based intuitive system and the screen-based general control system to compare the experiences and training effects. The results show that the HMD-based system can give a much better user experience and is easy to use. Three of the five components of a VR training system,namely, the user, the tasks, and software and database should be given more attention in future research.With more available technologies of input and output devices, VR engines, and system software, the VR training system will eventually yield much better training results, and will play a more important role in as a training tool for mine safety.展开更多
Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of maki...Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator’s Garden. Translating building data to the Virtual Reality Modeling Language (VRML) is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-of- detail switching.展开更多
In the realm of virtual reality(VR),haptic feedback is integral to enhance the immersive experience;yet,existing wearable devices predominantly rely on skin contact feedback,lacking options for compact and non-contact...In the realm of virtual reality(VR),haptic feedback is integral to enhance the immersive experience;yet,existing wearable devices predominantly rely on skin contact feedback,lacking options for compact and non-contact breeze-sense feedback.Herein,we propose a compact and non-contact working model piezoelectret actuator for providing a gentle and safe breeze sensation.This easy-fabricated and flexible breeze-sense generator with thickness around 1 mm generates air flow pressure up to~163 Pa,which is significantly sensed by human skin.In a typical demonstration,the breeze-sense generators array showcases its versatility by employing multiple coded modes for non-contact information transmitting.The thin thinness and good flexibility facilitate seamless integration with wearable VR setups,and the wearable arrays empower volunteers to precisely perceive the continuous and sudden breeze senses in the virtual environments.This work is expected to inspire developing new haptic feedback devices that play pivotal roles in human-machine interfaces for VR applications.展开更多
Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color...Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color pixels,the fluorescent color conversion layer inevitably includes green and red pixels.To fabricate such sort of display kits,inkjet printing is a promising way to position the color conversion layers.In this review article,the progress of AR/VR technologies is first reviewed,and in succession,the state of the art of inkjet printing,as well as two key issues-the optimization of ink and the reduction of coffee-ring effects,are introduced.Finally,some potential problems associated with the color converting layer are highlighted.展开更多
A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinema...A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinematics equat!ons of RFP are formulated; followed by applying a method of modeling using 3DMAX software to build an RFP＇s 3D geometric model before a 3D kinematics simulation system of RFP is completed based on virtual reality technology and Open Inventor VC ＋ ＋. Test results have indicated that this system can perform RFP＇s kinematics simulation in virtual environment. It can also imitate RFP＇s motion states and environmental features well. Moreover, not only can better real-time performances and interactions be achieved but also operator＇s vision telepresence be enhanced, therefore this approach may help lay the foundation for the realization of RFP＇s teleoperation with vision telepresence.展开更多
Virtual environment has been widely applied in scientific research and considered as an important tool of exploring science. But constructing a real virtual environment is rather difficult. The difficulty cannot be co...Virtual environment has been widely applied in scientific research and considered as an important tool of exploring science. But constructing a real virtual environment is rather difficult. The difficulty cannot be compared with developing general software. It has a high demand for software technology. Obviously traditional methods are not competent for the job. Fortunately with the development of agent-oriented technologies, all problems seem to be solved. By classifying a virtual environment into four layers corresponding with real world and considering it as a collection of agents, the virtual objects can be mapped into agents and an agent model can be designed. Based on the idea that the state change of a system is caused by that of individuals and the mutual effect among them, a theory of agent behavior driven by event and belief is put forward. Such agent-oriented modeling method can cope with the demand for handling multi-dimension information. It is an effective technique for constructing a large and complex virtual environment.展开更多
A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision ...A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision detection algorithm. By decomposing the whole space into relative positions and geometric features of the sphere and the primitive considered, closed form distance formula are got. These calculations are very useful in the real time collision detection in which primitives are used as bounding volumes of complex objects.展开更多
A calibration scheme under spherical coordinates is described for a magnetic tracker used in VR (virtual reality) system. A look up table containing data of tracked values for certain positions in the working space, ...A calibration scheme under spherical coordinates is described for a magnetic tracker used in VR (virtual reality) system. A look up table containing data of tracked values for certain positions in the working space, spe cified in spherical coordinates, is generated first, which is then used to calibrate the tracking results by a two dimensional interpolation. The scheme can effectively correct the static errors in the magnetic tracking system. The employment of spherical coordinates significantly reduces the calculation complexity in calibration.展开更多
A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, ...A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.展开更多
Relative preferences of 90 images of forest stands, photos and virtual reality images were investigated by the intemet to develop a quantitative model for estimating scenic beauty preferences at the stand level, The r...Relative preferences of 90 images of forest stands, photos and virtual reality images were investigated by the intemet to develop a quantitative model for estimating scenic beauty preferences at the stand level, The relative priority values obtained from the questionnaire of a total of 259 judges were analyzed using regression methods for pairwise comparisons. Two models were developed based on two different groups of stands. Both models indicate that the priority of a forest stand increases with an augment in the number of bushes and trees, and also with the mean diameter of trees. On the other hand, the priority is low with large number of pines and small trees. Stands represented by photos receive better priority values than those represented by virtual reality images. When the background of the judges （gender, country or occupation） was included into the model as additional predictors, no significant improvements are achieved.展开更多
This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission perform...This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAsmultiple quantum well （MQW） was used to increase the differential gain and photon density in VCSEL. The multiple oxidelayers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode （SM） VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.展开更多
Modem surface mines, either mono-system or multi-systems, need a large fleet of equipment consisting of excavators, loaders, haulers and auxiliary machines. Presently, the complexity of the system, the interference be...Modem surface mines, either mono-system or multi-systems, need a large fleet of equipment consisting of excavators, loaders, haulers and auxiliary machines. Presently, the complexity of the system, the interference between sub-systems and the lag in management skills has been a bottle neck for improving productivity of the system. Based on the fact that the traditional tools for safety analysis have been insufficient to evaluate systematically and dynamically the safety risks, this paper tries to create a virtual reality tool consisting of human, machine and mines, using Pro/E and the 3D MAX software in order to evaluate visually the operations of typical mining equipment, such as the bucket wheel excavator （BWE）, the shovel, the truck and the dragline. Within this virtual world, the behavior of the system, such as interaction, interference and potential risk can be replayed and reviewed visually. The objective of the study is to identify the critical safety issues of the system and to provide a convenient and powerful tool for safety training and safety management.展开更多
Virtual reality(VR)and augmented reality(AR)are revolutionizing our lives.Near-eye displays are crucial technologies for VR and AR.Despite the rapid advances in near-eye display technologies,there are still challenges...Virtual reality(VR)and augmented reality(AR)are revolutionizing our lives.Near-eye displays are crucial technologies for VR and AR.Despite the rapid advances in near-eye display technologies,there are still challenges such as large field of view,high resolution,high image quality,natural free 3D effect,and compact form factor.Great efforts have been devoted to striking a balance between visual performance and device compactness.While traditional optics are nearing their limitations in addressing these challenges,ultra-thin metasurface optics,with their high light-modulating capabilities,may present a promising solution.In this review,we first introduce VR and AR near-eye displays,and then briefly explain the working principles of light-modulating metasurfaces,review recent developments in metasurface devices geared toward near-eye display applications,delved into several advanced natural 3D near-eye display technologies based on metasurfaces,and finally discuss about the remaining challenges and future perspectives associated with metasurfaces for near-eye display applications.展开更多
Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs ...Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs is proper machine inspection.Traditional miner safety training includes the use of hardcopy documents and video instructions.However,modern mobile and computer technology offers tremendous potential to improve the training process.In this study,we apply a 360-degree camera,opensource platform WordPress^(TM),and the software Unity3D in order to create materials and tools for the HEOs safety training to help trainees better understand the pre-shift safety machine inspection.The computer-based safety task training developed in this research is tested and implemented at a surface mine in the southern United States.展开更多
This paper presents the results of a concept capability demonstration pilot study, the aim of which was to investigate how inexpensive gaming software and hardware technologies could be exploited in the development an...This paper presents the results of a concept capability demonstration pilot study, the aim of which was to investigate how inexpensive gaming software and hardware technologies could be exploited in the development and evaluation of a simulator prototype for training Royal Navy mine clearance divers, specifically focusing on the detection and accurate reporting of the location and condition of underwater ordnance. The simulator was constructed using the Blender open source 3D modelling toolkit and game engine, and featured not only an interactive 3D editor for underwater scenario generation by instructors, but also a real-time, 3D After Action Review(AAR) system for formative assessment and feedback.The simulated scenarios and AAR architecture were based on early human factors observations and briefings conducted at the UK's Defence Diving School(DDS), an organisation that provides basic military diving training for all Royal Navy and Army(Royal Engineers) divers. An experimental pilot study was undertaken to determine whether or not basic navigational and mine detection components of diver performance could be improved as a result of exposing participants to the AAR system, delivered between simulated diving scenarios. The results suggest that the provision of AAR was accompanied by significant performance improvements in the positive identification of simulated underwater ordnance(in contrast to non-ordnance objects) and on participants' description of their location, their immediate in-water or seabed context and their structural condition. Only marginal improvements were found with participants' navigational performance in terms of their deviation accuracies from a pre-programmed expert search path. Overall, this project contributes to the growing corpus of evidence supporting the development of simulators that demonstrate the value of exploiting open source gaming software and the significance of adopting established games design techniques in delivering highly engaging scenarios to defence training communities.展开更多
Computer Assisted Rehabilitation Environment(CAREN) is a system that integrates a training platform(motion base), a virtual environment, a sensor system(motion capture) and D-flow software. It is useful for both diagn...Computer Assisted Rehabilitation Environment(CAREN) is a system that integrates a training platform(motion base), a virtual environment, a sensor system(motion capture) and D-flow software. It is useful for both diagnostic and therapeutic use. The human gait pattern can be impaired due to disease, trauma or natural decline. Gait analysis is a useful tool to identify impaired gait patterns. Traditional gait analysis is a very time consuming process and therefore only used in exceptional cases. With new systems a quick and extensive analysis is possible and provides useful tools for therapeutic purposes. The range of systems will be described in this paper, highlighting both their diagnostic use and the therapeutic possibilities. Because wounded warriors often have an impaired gait due to amputations or other extremity trauma, these systems are very useful for military rehabilitative efforts. Additionally, the virtual reality environment creates a very challenging situation for the patient, enhancing their rehabilitation experience. For that reason several Armed Forces have these systems already in use. The most recent experiences will be discussed; including new developments both in the extension of the range of systems and the improvement and adaptation of the software. A new and promising development, the use of CAREN in a special application for patients with posttraumatic stress disorder(PTSD), will also be reviewed.展开更多
To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to suppor...To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to support both customers＇and design team members＇involvement in the conceptual design and analysis activity over the Internet. It provides users with both parametric and freehand methods to create and edit 3D conceptual models with different levels of complexity in a VR environment intuitively without the need of switching between the VR environment and CAD tools. As a simple and low-cost VR-CAD system, WVCD can help to popularize and improve the Web-based collaborative conceptual design.展开更多
文摘A catadioptric lens structure,also known as pancake lens,has been widely used in virtual reality(VR)displays to reduce the formfactor.However,the utilization of a half mirror(HM)to fold the optical path thrice leads to a significant optical loss.The theoretical maximum optical efficiency is merely 25%.To transcend this optical efficiency constraint while retaining the foldable characteristic inherent to traditional pancake optics,in this paper,we propose a theoretically lossless folded optical system to replace the HM with a nonreciprocal polarization rotator.In our feasibility demonstration experiment,we used a commercial Faraday rotator(FR)and reflective polarizers to replace the lossy HM.The theoretically predicted 100%efficiency can be achieved approximately by using two high-extinction-ratio reflective polarizers.In addition,we evaluated the ghost images using a micro-OLED panel in our imaging system.Indeed,the ghost images can be suppressed to undetectable level if the optics are with antireflection coating.Our novel pancake optical system holds great potential for revolutionizing next-generation VR displays with lightweight,compact formfactor,and low power consumption.
文摘The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation algorithm is proposed based on the geometric analysis and the angular propagation （AP）, and a 3-D real-time interactive system is developed for the motion simulation of the guide wire and the catheter inside the specific patient vascular. The guide wire or the catheter is modeled as the ＂multi-body＂ representation and properties are defined by its intrinsic characteristics. The motion of the guide wire or the catheter inside the vascular is guided by the collision detection and the collision cancellation algorithm. Finally, a relaxation procedure is used to achieve more realistic status. Experimental results show that the behavior of the guide wire or the catheter depends on the defined parameters. The real-time simulation can be achieved. The result shows that the simulation system is effective and promising.
基金funded by the ‘‘twelfth five” National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2015BAK10B00)
文摘Virtual reality(VR) training technology in the mining industry is a new field of research and utilization.The successful application of VR training system is critical to mine safety and production. Through the statistics of the current research and applications of VR training systems in mining industry, all the input/output devices are classified. Based on the classifications of the input/output devices that are used in the VR system, the current VR training systems for the mining industry could be divided into three types: screen-based general type, projector-based customized type, and head-mounted display(HMD)-based intuitive type. By employing a VR headset, a smartphone and a leap motion device, an HMDbased intuitive type VR training system prototype for drilling in underground mines has been developed.Ten trainees tried both the HMD-based intuitive system and the screen-based general control system to compare the experiences and training effects. The results show that the HMD-based system can give a much better user experience and is easy to use. Three of the five components of a VR training system,namely, the user, the tasks, and software and database should be given more attention in future research.With more available technologies of input and output devices, VR engines, and system software, the VR training system will eventually yield much better training results, and will play a more important role in as a training tool for mine safety.
基金Funded by the Natural Science Foundation of China (No. 50378037)
文摘Using virtual reality for interactive design gives a designer an intuitive vision of a design and allows the designer to achieve a viable, optimal solution in a timely manner. The article discusses the process of making the Virtual Reality System of the Humble Administrator’s Garden. Translating building data to the Virtual Reality Modeling Language (VRML) is by far unsatisfactory. This creates a challenge for computer designers to do optimization to meet requirements. Five different approaches to optimize models have been presented in this paper. The other methods are to optimize VRML and to reduce the file size. This is done by keeping polygon counts to a minimum and by applying such techniques as object culling and level-of- detail switching.
基金supported by the Science and Technology Development Fund of Macao SAR(File No.0117/2024/AMJ)University of Macao(MYRG-GRG2023-00041-FST-UMDF,MYRG-GRG2024-00121-FST,MYRG-CRG2024-00014-FST-ICI)Zhuhai UM Science&Technology Research Institute(CP-009-2024).
文摘In the realm of virtual reality(VR),haptic feedback is integral to enhance the immersive experience;yet,existing wearable devices predominantly rely on skin contact feedback,lacking options for compact and non-contact breeze-sense feedback.Herein,we propose a compact and non-contact working model piezoelectret actuator for providing a gentle and safe breeze sensation.This easy-fabricated and flexible breeze-sense generator with thickness around 1 mm generates air flow pressure up to~163 Pa,which is significantly sensed by human skin.In a typical demonstration,the breeze-sense generators array showcases its versatility by employing multiple coded modes for non-contact information transmitting.The thin thinness and good flexibility facilitate seamless integration with wearable VR setups,and the wearable arrays empower volunteers to precisely perceive the continuous and sudden breeze senses in the virtual environments.This work is expected to inspire developing new haptic feedback devices that play pivotal roles in human-machine interfaces for VR applications.
基金supported by the National Natural Science Foundation of China (11904302)the Fundamental Research Funds for the Central Universities (Grant No.20720190005)+1 种基金the Major Science and Technology Project of Xiamen in China (3502Z20191015)Hong Kong University of Science and Technology-Foshan Joint Research Program (FSUST19-FYTRI11)
文摘Augmented reality(AR)and virtual reality(VR)are two novel display technologies that are under updates.The essential feature of AR/VR is the full-color display that requires high pixel densities.To generate three-color pixels,the fluorescent color conversion layer inevitably includes green and red pixels.To fabricate such sort of display kits,inkjet printing is a promising way to position the color conversion layers.In this review article,the progress of AR/VR technologies is first reviewed,and in succession,the state of the art of inkjet printing,as well as two key issues-the optimization of ink and the reduction of coffee-ring effects,are introduced.Finally,some potential problems associated with the color converting layer are highlighted.
基金Sponsored by Independent Research Projects of State Key Laboratory (ZDKT08-05)
文摘A method of 3 D kinematics simulation of robot fighting platform （RFP） in virtual environment is proposed with the aim of enhancing vision telepresence. Based on the theory of space coordinate transformation, kinematics equat!ons of RFP are formulated; followed by applying a method of modeling using 3DMAX software to build an RFP＇s 3D geometric model before a 3D kinematics simulation system of RFP is completed based on virtual reality technology and Open Inventor VC ＋ ＋. Test results have indicated that this system can perform RFP＇s kinematics simulation in virtual environment. It can also imitate RFP＇s motion states and environmental features well. Moreover, not only can better real-time performances and interactions be achieved but also operator＇s vision telepresence be enhanced, therefore this approach may help lay the foundation for the realization of RFP＇s teleoperation with vision telepresence.
文摘Virtual environment has been widely applied in scientific research and considered as an important tool of exploring science. But constructing a real virtual environment is rather difficult. The difficulty cannot be compared with developing general software. It has a high demand for software technology. Obviously traditional methods are not competent for the job. Fortunately with the development of agent-oriented technologies, all problems seem to be solved. By classifying a virtual environment into four layers corresponding with real world and considering it as a collection of agents, the virtual objects can be mapped into agents and an agent model can be designed. Based on the idea that the state change of a system is caused by that of individuals and the mutual effect among them, a theory of agent behavior driven by event and belief is put forward. Such agent-oriented modeling method can cope with the demand for handling multi-dimension information. It is an effective technique for constructing a large and complex virtual environment.
文摘A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision detection algorithm. By decomposing the whole space into relative positions and geometric features of the sphere and the primitive considered, closed form distance formula are got. These calculations are very useful in the real time collision detection in which primitives are used as bounding volumes of complex objects.
文摘A calibration scheme under spherical coordinates is described for a magnetic tracker used in VR (virtual reality) system. A look up table containing data of tracked values for certain positions in the working space, spe cified in spherical coordinates, is generated first, which is then used to calibrate the tracking results by a two dimensional interpolation. The scheme can effectively correct the static errors in the magnetic tracking system. The employment of spherical coordinates significantly reduces the calculation complexity in calibration.
文摘A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.
文摘Relative preferences of 90 images of forest stands, photos and virtual reality images were investigated by the intemet to develop a quantitative model for estimating scenic beauty preferences at the stand level, The relative priority values obtained from the questionnaire of a total of 259 judges were analyzed using regression methods for pairwise comparisons. Two models were developed based on two different groups of stands. Both models indicate that the priority of a forest stand increases with an augment in the number of bushes and trees, and also with the mean diameter of trees. On the other hand, the priority is low with large number of pines and small trees. Stands represented by photos receive better priority values than those represented by virtual reality images. When the background of the judges （gender, country or occupation） was included into the model as additional predictors, no significant improvements are achieved.
文摘This paper is going to review the state-of-the-art of the high-speed 850/940-nm vertical cavity surface emitting laser（VCSEL）, discussing the structural design, mode control and the related data transmission performance. InGaAs/AlGaAsmultiple quantum well （MQW） was used to increase the differential gain and photon density in VCSEL. The multiple oxidelayers and oxide-confined aperture were well designed in VCSEL to decrease the parasitic capacitance and generate single mode （SM） VCSEL. The maximal modulation bandwidth of 30 GHz was achieved with well-designed VCSEL structure. At the end of the paper, other applications of the near-infrared VCSELs are discussed.
基金Project 2002CB412705 supported by the Major State Basic Research Development Program (973) of China
文摘Modem surface mines, either mono-system or multi-systems, need a large fleet of equipment consisting of excavators, loaders, haulers and auxiliary machines. Presently, the complexity of the system, the interference between sub-systems and the lag in management skills has been a bottle neck for improving productivity of the system. Based on the fact that the traditional tools for safety analysis have been insufficient to evaluate systematically and dynamically the safety risks, this paper tries to create a virtual reality tool consisting of human, machine and mines, using Pro/E and the 3D MAX software in order to evaluate visually the operations of typical mining equipment, such as the bucket wheel excavator （BWE）, the shovel, the truck and the dragline. Within this virtual world, the behavior of the system, such as interaction, interference and potential risk can be replayed and reviewed visually. The objective of the study is to identify the critical safety issues of the system and to provide a convenient and powerful tool for safety training and safety management.
基金supports from the National Key Research and Development Program of China (2021YFB2802100)the National Natural Science Foundation of China (62075127 and 62105203).
文摘Virtual reality(VR)and augmented reality(AR)are revolutionizing our lives.Near-eye displays are crucial technologies for VR and AR.Despite the rapid advances in near-eye display technologies,there are still challenges such as large field of view,high resolution,high image quality,natural free 3D effect,and compact form factor.Great efforts have been devoted to striking a balance between visual performance and device compactness.While traditional optics are nearing their limitations in addressing these challenges,ultra-thin metasurface optics,with their high light-modulating capabilities,may present a promising solution.In this review,we first introduce VR and AR near-eye displays,and then briefly explain the working principles of light-modulating metasurfaces,review recent developments in metasurface devices geared toward near-eye display applications,delved into several advanced natural 3D near-eye display technologies based on metasurfaces,and finally discuss about the remaining challenges and future perspectives associated with metasurfaces for near-eye display applications.
文摘Improving the quality of equipment training for the Heavy Equipment Operators(HEO)is a critical task in improving safety and eliminating equipment-related injuries in mining.One of major responsibilities for the HEOs is proper machine inspection.Traditional miner safety training includes the use of hardcopy documents and video instructions.However,modern mobile and computer technology offers tremendous potential to improve the training process.In this study,we apply a 360-degree camera,opensource platform WordPress^(TM),and the software Unity3D in order to create materials and tools for the HEOs safety training to help trainees better understand the pre-shift safety machine inspection.The computer-based safety task training developed in this research is tested and implemented at a surface mine in the southern United States.
基金undertaken as part of a University of Birmingham Year 4(MEng)Final Year Project,with funding made available from internal resources at the University of Birmingham’s School of Electronic,Electrical&Systems Engineering
文摘This paper presents the results of a concept capability demonstration pilot study, the aim of which was to investigate how inexpensive gaming software and hardware technologies could be exploited in the development and evaluation of a simulator prototype for training Royal Navy mine clearance divers, specifically focusing on the detection and accurate reporting of the location and condition of underwater ordnance. The simulator was constructed using the Blender open source 3D modelling toolkit and game engine, and featured not only an interactive 3D editor for underwater scenario generation by instructors, but also a real-time, 3D After Action Review(AAR) system for formative assessment and feedback.The simulated scenarios and AAR architecture were based on early human factors observations and briefings conducted at the UK's Defence Diving School(DDS), an organisation that provides basic military diving training for all Royal Navy and Army(Royal Engineers) divers. An experimental pilot study was undertaken to determine whether or not basic navigational and mine detection components of diver performance could be improved as a result of exposing participants to the AAR system, delivered between simulated diving scenarios. The results suggest that the provision of AAR was accompanied by significant performance improvements in the positive identification of simulated underwater ordnance(in contrast to non-ordnance objects) and on participants' description of their location, their immediate in-water or seabed context and their structural condition. Only marginal improvements were found with participants' navigational performance in terms of their deviation accuracies from a pre-programmed expert search path. Overall, this project contributes to the growing corpus of evidence supporting the development of simulators that demonstrate the value of exploiting open source gaming software and the significance of adopting established games design techniques in delivering highly engaging scenarios to defence training communities.
文摘Computer Assisted Rehabilitation Environment(CAREN) is a system that integrates a training platform(motion base), a virtual environment, a sensor system(motion capture) and D-flow software. It is useful for both diagnostic and therapeutic use. The human gait pattern can be impaired due to disease, trauma or natural decline. Gait analysis is a useful tool to identify impaired gait patterns. Traditional gait analysis is a very time consuming process and therefore only used in exceptional cases. With new systems a quick and extensive analysis is possible and provides useful tools for therapeutic purposes. The range of systems will be described in this paper, highlighting both their diagnostic use and the therapeutic possibilities. Because wounded warriors often have an impaired gait due to amputations or other extremity trauma, these systems are very useful for military rehabilitative efforts. Additionally, the virtual reality environment creates a very challenging situation for the patient, enhancing their rehabilitation experience. For that reason several Armed Forces have these systems already in use. The most recent experiences will be discussed; including new developments both in the extension of the range of systems and the improvement and adaptation of the software. A new and promising development, the use of CAREN in a special application for patients with posttraumatic stress disorder(PTSD), will also be reviewed.
文摘To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to support both customers＇and design team members＇involvement in the conceptual design and analysis activity over the Internet. It provides users with both parametric and freehand methods to create and edit 3D conceptual models with different levels of complexity in a VR environment intuitively without the need of switching between the VR environment and CAD tools. As a simple and low-cost VR-CAD system, WVCD can help to popularize and improve the Web-based collaborative conceptual design.
