Yaoping Hu - Academia.edu (original) (raw)

Papers by Yaoping Hu

Lecture Notes in Computer Science, 2017

Navigation is a key factor for immersion and exploration in virtual environment (VE). Nevertheles... more Navigation is a key factor for immersion and exploration in virtual environment (VE). Nevertheless, measuring navigation performance is not an easy task, especially when analyzing and interpreting heterogeneous results of the measures used. To that end, we propose, in this paper, a new indicator for measuring navigation performance in VE based on ISO/IEC 15939 standard. It allows effective integration of heterogeneous results by retaining its raw values. Also, it provides a new method that offers a comprehensive graphical visualization of the data for interpreting the results. The experimental study had shown the feasibility of this indicator and its contribution to statistical results.

2017 IEEE Virtual Reality (VR), 2017

Proper integration of sensory cues facilitates 3D user interaction within virtual environments (V... more Proper integration of sensory cues facilitates 3D user interaction within virtual environments (VEs). Studies showed that the integration of visual and haptic cues follows maximum likelihood estimation (MLE). Little effort focuses however on the mechanism of integrating force and vibrotactile cues. We thus investigated MLE's suitability for integrating these cues. Within a VE, human users undertook 3D interaction of navigating a flying drone along a high-voltage transmission line for inspection. The users received individual force or vibrotactile cues, and their combinations in collocated and dislocated settings. The users' task performance including completion time and accuracy was assessed under each individual cue and setting. The presence of the vibrotactile cue promoted a better performance than the force cue alone. This agreed with the applicability of tactile cues for sensing 3D surfaces, herein setting a baseline for using MLE. The task performance under the collocated setting indicated a degree of combining the individual cues. In contrast, the performance under the dislocated setting was alike under the individual vibrotactile cue. These observations imply a possible role of MLE in integrating force and vibrotactile cues for 3D user interaction within VEs.

2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006

Study has shown that three-dimensional (3D) visualization of lung cavities has distinct advantage... more Study has shown that three-dimensional (3D) visualization of lung cavities has distinct advantages over traditional computed tomographic (CT) images for surgical planning. A crucial step for achieving 3D visualization of lung cavities is the segmentation of lung lobes by identifying lobar fissures in volumetric CT images. Current segmentation algorithms for lung lobes rely on manually placed markers to identify the fissures. This paper presents an autonomous algorithm that effectively segments the lung lobes without user intervention. This algorithm applies a two-stage approach: (a) adaptive fissure sweeping to coarsely define fissure regions of lobar fissures; and (b) watershed transform to refine the location and curvature of fissures within the fissure regions. We have tested this algorithm on 4 CT data sets. Comparing with visual inspection, the algorithm provides an accuracy of 85.5-95.0% and 88.2-92.3% for lobar fissures in the left and right lungs, respectively. This work proves the feasibility of developing an automatic algorithm for segmenting lung lobes.

2017 IEEE Symposium on 3D User Interfaces (3DUI), 2017

Proper integration of sensory cues facilitates 3D user interaction within virtual environments (V... more Proper integration of sensory cues facilitates 3D user interaction within virtual environments (VEs). Studies on multi-sensory integration of visual and haptic cues revealed that the integration follows maximum likelihood estimation (MLE). Little effort focuses however on integrating force and vibrotactile cues-two sub-categorical cues of the haptic modality. Hence, this paper presents an investigation on MLE's suitability for integrating these sub-categorical cues. Within a stereoscopic VE, human users performed a 3D interactive task of navigating a flying drone along a high-voltage transmission line in an inaccessible region and identifying defects on the line. The users had to identify defects via individual force or vibrotactile cues, and their combinations in colocated and dislocated settings. The co-located setting provided both cues on the right hand of the users; whereas the dislocated setting delivered the force and vibrotactile cues on the right hand and forearm of the users, respectively. Task performance of the users, such as completion time and accuracy, was assessed under each cue and setting. The presence of the vibrotactile cue promoted a better performance than the force cue alone. This was in agreement with the role of tactile cues in sensing surface properties, herein setting a baseline for using MLE. The task performance under the co-located setting indicated certain degrees of combining those under the individual cues. In contrast, the performance under the dislocated setting was alike that under the individual vibrotactile cue. These observations imply an inconclusiveness of MLE to integrate both cues in a co-located setting for 3D user interaction.

2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), 2019

Current virtual environments (VE) enable perceiving haptic stimuli to facilitate 3D user interact... more Current virtual environments (VE) enable perceiving haptic stimuli to facilitate 3D user interaction, but lack brain-interfacial contents. Using electroencephalography (EEG), we undertook a feasibility study on exploring event-related potential (ERP) patterns of the user's brain responses during haptic interaction within a VE. The interaction was flying a virtual drone along a curved transmission line to detect defects under the stimuli (e.g., force increase and/or vibrotactile cues). We found that there were variations in the peak amplitudes and latencies (as ERP patterns) of the responses at about 200 ms post the onset of the stimuli. The largest negative peak occurred during 200~400 ms after the onset in all vibration-related blocks. Moreover, the amplitudes and latencies of the peak were differentiable among the vibration-related blocks. These findings imply feasible decoding of the brain responses during haptic interaction within VEs.

Journal of Visualization, 2019

Turbulent vortex shedding in the wake of a bluff body often contains cycle-to-cycle variations in... more Turbulent vortex shedding in the wake of a bluff body often contains cycle-to-cycle variations in the shape, trajectory, and intensity of vortices. Existing flow visualization techniques cannot effectively present these variations and, consequently, their influence on the aerodynamics to the user. This paper explores a new flow visualization approach to represent quasi-periodic vortex shedding over multiple shedding cycles concurrently. This approach uses a reduced-dimension representation of spatiotemporal vortex progression (called evolution surfaces) and ensemble visualization techniques (clustering). The resulting visualization can be used to identify topological changes in the behavior and strengths of coherent structures (i.e. vortices) in unsteady flows. This approach is applied in two case studies of bluff body wakes with Reynolds Numbers Re = 1200 (Hemmati et al. 2016c) and Re = 300 (Morton et al. 2018). In prior work, classification of these wakes' dynamics was based on energy fluctuation and shedding topology. However, these techniques are not well suited for representing characteristic changes between shedding regimes. In the present work, it has been shown that evolution surface clusters help to identify topological changes characterizing cycle-to-cycle variations in vortex behavior, while reducing visual clutter. The results indicate that evolution surface clusters are a promising visualization tool for comparative analysis of unsteady vortex dynamics in turbulent wakes.

Applied Sciences, 2017

Collaborative virtual environments (CVEs) present ways for human users to work together on a task... more Collaborative virtual environments (CVEs) present ways for human users to work together on a task. Research efforts of CVEs have mainly focused on the factors that affect the task performance of the users, such as awareness, communication, and presence. Furthermore, the users involved normally have the same task experience or knowledge background. In this paper, we examined the effect of interactive strategies for human/human interaction, which involves human users with different levels of expertise. Within a CVE for an expert and a novice, we deployed three interactive strategies-Tele-Operation, Tele-Assistance3, and Tele-Assistance7-to give the three degrees of autonomy to the novice. Focusing on the performance of the novice, our findings revealed that each interactive strategy has a different effect on the task performance of the novice. These findings could aid in choosing an optimal interactive strategy for performing a collaborative task between an expert and a novice.

2016 IEEE Symposium on 3D User Interfaces (3DUI), 2016

4 CONCLUSION AND FUTURE WORK This work revealed that the compass pattern yields better performanc... more 4 CONCLUSION AND FUTURE WORK This work revealed that the compass pattern yields better performance of navigation than the pushing pattern. This indicates a potential of using the compass pattern to facilitate navigation in VEs. Future work includes the refinement of the compass pattern for reducing cybersickness.

IEEE SMC'99 Conference Proceedings. 1999 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.99CH37028)

We conducted two experiments to compare the visual frames of reference used to scale grasping mov... more We conducted two experiments to compare the visual frames of reference used to scale grasping movements directed at objects with those used to estimate the size of the same objects-either immediately or after a 5-s delay. A virtual "workbench" was employed for presenting two different-sized objects in 3D. Subjects were instructed to pick up or estimate the marked one of the two objects. We found that the presence of the other object affected not only the estimate of the size of the target object when subjects made their estimates both immediately and after a 5-s delay, but also the scaling of grip aperture in flight when subjects picked up the target object after a 5-s delay. However, when subjects picked up the target object immediately, their grasp was scaled to the actual size of the target object and was not influenced by the presence of the other object. These findings suggest that the control of delayed motor actions utilizes the same relative metrics in allocentric frames of reference used by conscious perception, whereas the control of normal visually guided motor actions relies on absolute metrics in egocentric frames of reference. Implications of these findings for the design of human-machine interfaces are discussed.

Proceedings of the 9th IEEE International Conference on Collaborative Computing: Networking, Applications and Worksharing, 2013

Multiuser collaborative virtual environments (VEs) need strategies of conflict resolution to hand... more Multiuser collaborative virtual environments (VEs) need strategies of conflict resolution to handle simultaneous interaction with shared objects. Current strategies are first-comefirst-serve (FCFS) and predefined static priority of each user. These strategies cannot provide each user with a perceived equal opportunity of interaction and often lead to perceived unfairness to abandon collaboration. To offer an equal opportunity, we created a dynamic priority (DP) strategy and compared the strategy with the FCFS strategy based upon subjective perception of multiple users. Visual or haptic (pertinent to the sense of touch) cues assisted each user to perceive his/her gaining of interaction. We observed that the DP strategy yielded significantly an equal opportunity of interaction. The haptic cue offered lower variations in perceiving the equality than the visual cue under the DP strategy. These observations imply a potential application of the DP strategy in a VE, where various experts require equal opportunities in collaboration.

Canadian Journal of Surgery, 2013

Feasibility and fidelity of practising surgical fixation on a virtual ulna bone Background: Surgi... more Feasibility and fidelity of practising surgical fixation on a virtual ulna bone Background: Surgical simulators provide a safe environment to learn and practise psychomotor skills. A goal for these simulators is to achieve high levels of fidelity. The purpose of this study was to develop a reliable surgical simulator fidelity questionnaire and to assess whether a newly developed virtual haptic simulator for fixation of an ulna has comparable levels of fidelity as Sawbones. Methods: Simulator fidelity questionnaires were developed. We performed a stratified randomized study with surgical trainees. They performed fixation of the ulna using a virtual simulator and Sawbones. They completed the fidelity questionnaires after each procedure. Results: Twenty-two trainees participated in the study. The reliability of the fidelity questionnaire for each separate domain (environment, equipment, psychological) was Cronbach α greater than 0.70, except for virtual environment. The Sawbones had significantly higher levels of fidelity than the virtual simulator (p < 0.001) with a large effect size difference (Cohen d < 1.3). Conclusion: The newly developed fidelity questionnaire is a reliable tool that can potentially be used to determine the fidelity of other surgical simulators. Increasing the fidelity of this virtual simulator is required before its use as a training tool for surgical fixation. The virtual simulator brings with it the added benefits of repeated, independent safe use with immediate, objective feedback and the potential to alter the complexity of the skill. Contexte : Les simulateurs chirurgicaux offrent un environnement sécuritaire pour apprendre et pour exercer les habiletés psychomotrices. L'un des objectifs de ces simulateurs est de produire des degrés élevés de fidélité. Le but de cette étude était de mettre au point un questionnaire fiable sur la fidélité des simulateurs chirurgicaux et de vérifier si un nouveau simulateur virtuel, avec interface haptique, pour la fixation du cubitus présentait des taux de fidélité comparables à ceux du simulateur Sawbones. Méthodes : Des questionnaires sur la fidélité des simulateurs ont été préparés. Nous avons procédé à une étude randomisée stratifiée auprès de stagiaires en chirurgie qui ont effectué une fixation du cubitus à l'aide du simulateur virtuel et à l'aide du simulateur Sawbones. Ils ont répondu au questionnaire sur la fidélité après chaque intervention. Résultats : Vingt-deux stagiaires ont participé à l'étude. La fiabilité du questionnaire sur la fidélité pour chaque domaine distinct (environnement, équipement, dimension psychologique) correspondait à un coefficient α Cronbach supérieur à 0,70, sauf pour ce qui est de l'environnement virtuel. Le simulateur Sawbones a présenté des taux de fidélité significativement plus élevés que le simulateur virtuel (p < 0,001), avec une différence importante au plan de la taille de l'effet (indice d de Cohen < 1,3). Conclusion : Le nouveau questionnaire sur la fidélité s'est révélé un outil fiable qui peut servir à déterminer le degré de fidélité d'autres simulateurs chirurgicaux. Il faudra améliorer la fidélité de ce simulateur virtuel avant de pouvoir l'utiliser comme outil de formation pour la fixation chirurgicale. Ce simulateur virtuel a l'avantage de permettre des utilisations sécuritaires répétées et indépendantes avec des résultats immédiats et objectifs et de modifier la complexité de l'habileté. S urgical simulators provide a safe environment where a surgical trainee can learn and practise psychomotor skills. A goal for these simulators is to achieve high levels of fidelity so that they can be used in surgical curricula. The fidelity of a simulator is important, as it helps determine the extent to which a trainee is able to learn from the simulated experience and transfer the learning to the real environment. Fidelity can be defined as the

Fourth IEEE Conference on Cognitive Informatics, 2005. (ICCI 2005)., 2005

ABSTRACT

2011 IEEE World Haptics Conference, 2011

Virtual Reality (VR) technology has great potential as a tool for training. Remote haptic virtual... more Virtual Reality (VR) technology has great potential as a tool for training. Remote haptic virtual environments (VE) allow multiple users to interact in the same virtual space to accomplish tasks. Combining these ideas, it is possible to apply a remote VE to connect skilled trainers with remote trainees for training. In this paper we examined guided haptic training as an

Journal of Cognitive Neuroscience, 2000

We carried out three experiments designed to compare the effects of relative and absolute size on... more We carried out three experiments designed to compare the effects of relative and absolute size on manual prehension and manual estimates of perceived size. In each experiment, right-handed subjects were presented with two different-sized 3-D objects in a virtual display and were instructed to pick up or estimate the size of one of them. In Experiment 1, subjects were requested to pick up the smaller one of two virtual objects under one condition and the larger one under the other condition. In fact, the target object was identical on all trials; it was simply paired with a smaller object on some trials and a larger object on others. To provide veridical haptic feedback, a real object was positioned beneath a mirror at the same location as the virtual target object. In Experiment 2, one of the virtual objects was marked with a red dot on its top surface. From trial to trial, the marked object was paired with a larger, smaller, or same-sized object. Subjects were instructed to always ...

IEEE Transactions on Biomedical Engineering, 2009

Modernmultislice computed tomography (CT) scanners produce isotropic CT images with a thickness o... more Modernmultislice computed tomography (CT) scanners produce isotropic CT images with a thickness of 0.6 mm. These CT images offer detailed information of lung cavities, which could be used for better surgical planning of treating lung cancer. The major challenge for developing a surgical planning system is the automatic segmentation of lung lobes by identifying the lobar fissures. This paper presents a lobe segmentation algorithm that uses a twostage approach: 1) adaptive fissure sweeping to find fissure regions and 2) wavelet transform to identify the fissure locations and curvatures within these regions. Tested on isotropic CT image stacks from nine anonymous patients with pathological lungs, the algorithm yielded an accuracy of 76.7%-94.8% with strict evaluation criteria. In comparison, surgeons obtain an accuracy of 80% for localizing the fissure regions in clinical CT images with a thickness of 2.5-7.0 mm. As well, this paper describes a procedure for visualizing lung lobes in three dimensions using software-amira-and the segmentation algorithm. The procedure, including the segmentation, needed about 5 min for each patient. These results provide promising potential for developing an automatic algorithm to segment lung lobes for surgical planning of treating lung cancer.

Geoderma, 2010

For the investigation of many geometrical features of soils, computer-assisted image analysis has... more For the investigation of many geometrical features of soils, computer-assisted image analysis has become a method of choice over the last few decades. This analysis involves numerous steps, regarding which subjective decisions have to be made by the individuals conducting the research. This is particularly the case with the thresholding step, required to transform the original (color or greyscale) images into the type of binary representation (e.g., pores in white, solids in black) needed for fractal analysis or simulation with Lattice-Boltzmann models. Limited information exists at present on whether different observers, analyzing the same soil, would be likely to obtain similar results. In this general context, the first objective of the research reported in this article was to determine, through a so-called "round-robin" test, how much variation exists among the outcomes of various image thresholding strategies (including any image pretreatment deemed appropriate), routinely adopted by soil scientists. Three test imagesof a field soil, a soil thin section, and a virtual section through a 3-dimensional CT data setwere thresholded by 13 experts, worldwide. At the same time, variability of the outcomes of a set of automatic thresholding algorithms, applied to portions of the test images, was also investigated. The experimental results obtained illustrate the fact that experts rely on very different approaches to threshold images of soils, and that there is considerable observer influence associated with this thresholding. This observer dependence is not likely to be alleviated by adoption of one of the many existing automatic thresholding algorithms, many of which produce thresholded images that are equally, or even more, variable than those of the experts. These observations suggest that, at this point, analysis of the same image of a soil, be it a simple photograph or 3-dimensional X-ray CT data, by different individuals can lead to very different results, without any assurance that any of them would be even approximately "correct" or best suited to the objective at hand. Different strategies are proposed to cope with this situation, including the use of physical "standards", adoption of procedures to assess the accuracy of thresholding, benchmarking with physical measurements, or the development of computational methods that do not require binary images.

Experimental Brain Research, 2005

It has been repeatedly demonstrated that the opening between the index finger and thumb (grasp co... more It has been repeatedly demonstrated that the opening between the index finger and thumb (grasp component) during an object-directed reach-to-grasp movement achieves maximum aperture approximately two-thirds of the way through the duration of the reaching movement (transport component). Here we offer a quantitative model of the temporal coupling between grip aperture and wrist velocity which shows experimentally that the correlation between grip aperture and object size is a sigmoidal function of movement duration. When wrist velocity reaches its peak value, the correlation between the grip aperture and the size of the goal object has reached half of the correlation that is achieved by the end of the movement.

European Journal of Cardio-Thoracic Surgery, 2007

Objective: Three-dimensional (3D) displays of anatomic structures have become feasible for preope... more Objective: Three-dimensional (3D) displays of anatomic structures have become feasible for preoperative planning in some surgical procedures. There have been no reports, however, on the use of 3D displays for surgical treatment of lung cancer. We hypothesized that 3D displays of the thorax are useful for preoperative planning for lung cancer. Methods: Based on virtual reality technologies, we rendered 3D displays of the thorax from two-dimensional (2D) computed tomographic (CT) images of six anonymous patients, some of whom underwent surgical removal of lung cancer. For determining the resectability of lung cancer, we tested 17 participants with varying degrees of surgical skills to view 3D displays and read 2D CT images of these thoracic cavities in a randomized order. We measured their performance in terms of the accuracy of predicted resectability, the confidence of their prediction, planning time used, and workload experienced. Results: The results demonstrated that viewing 3D displays of thoracic cavities has significant advantages over reading 2D CT images in determining the resectability of lung cancer: increasing the accuracy of predicted resectability by about 20%, enhancing the confidence of the prediction by about 20%, decreasing planning time by about 30%, and reducing workload by about 50%. All participants preferred viewing 3D displays to reading 2D CT images for preoperative planning. Junior residents found 3D displays of thoraces more useful than senior residents. Conclusions: It is feasible to use 3D displays of the thorax for preoperative planning in treating lung cancer. Using 3D displays in surgical treatment of lung cancer has potential benefits, once the technique is perfected.

Biological Procedures Online, 2006

Microbes frequently live within multicellular, solid surface-attached assemblages termed biofilms... more Microbes frequently live within multicellular, solid surface-attached assemblages termed biofilms. These microbial communities have architectural features that contribute to population heterogeneity and consequently to emergent cell functions. Therefore, three-dimensional (3D) features of biofilm structure are important for understanding the physiology and ecology of these microbial systems. This paper details several protocols for scanning electron microscopy and confocal laser scanning microscopy (CLSM) of biofilms grown on polystyrene pegs in the Calgary Biofilm Device (CBD). Furthermore, a procedure is described for image processing of CLSM data stacks using amira™, a virtual reality tool, to create surface and/or volume rendered 3D visualizations of biofilm microorganisms. The combination of microscopy with microbial cultivation in the CBD-an apparatus that was designed for highthroughput susceptibility testing-allows for structure-function analysis of biofilms under multivariate growth and exposure conditions. Harrison et al.-The use of microscopy and three-dimensional visualization to evaluate the structure of microbial biofilms cultivated in the Calgary Biofilm Device www.biologicalprocedures.com

Biofouling, 2008

Quantitative parameters for describing the morphology of biofilms are crucial towards establishin... more Quantitative parameters for describing the morphology of biofilms are crucial towards establishing the influence of growing conditions on biofilm structure. Parameters used in earlier studies generally fail to differentiate complex three-dimensional structures. This article presents a novel approach of defining a parameter vector based on the energy signature of multi-resolution analysis, which was applied to differentiating biofilm structures from confocal laser scanning microscopy (CLSM) biofilm images. The parameter vector distinguished differences in the spatial arrangements of synthetic images. For real CLSM images, this parameter vector detected subtle differences in biofilm structure for three sample cases: (1) two adjacent images of a CLSM stack; (2) two partial stacks from the same CLSM stack with equal numbers of images but spatially offset by one image; and (3) three complete CLSM stacks from different bacterial strains. It was also observed that filtering the noise in CLSM images enhanced the sensitivity of the differentiation using our parameter vector.

Lecture Notes in Computer Science, 2017

Navigation is a key factor for immersion and exploration in virtual environment (VE). Nevertheles... more Navigation is a key factor for immersion and exploration in virtual environment (VE). Nevertheless, measuring navigation performance is not an easy task, especially when analyzing and interpreting heterogeneous results of the measures used. To that end, we propose, in this paper, a new indicator for measuring navigation performance in VE based on ISO/IEC 15939 standard. It allows effective integration of heterogeneous results by retaining its raw values. Also, it provides a new method that offers a comprehensive graphical visualization of the data for interpreting the results. The experimental study had shown the feasibility of this indicator and its contribution to statistical results.

2017 IEEE Virtual Reality (VR), 2017

Proper integration of sensory cues facilitates 3D user interaction within virtual environments (V... more Proper integration of sensory cues facilitates 3D user interaction within virtual environments (VEs). Studies showed that the integration of visual and haptic cues follows maximum likelihood estimation (MLE). Little effort focuses however on the mechanism of integrating force and vibrotactile cues. We thus investigated MLE's suitability for integrating these cues. Within a VE, human users undertook 3D interaction of navigating a flying drone along a high-voltage transmission line for inspection. The users received individual force or vibrotactile cues, and their combinations in collocated and dislocated settings. The users' task performance including completion time and accuracy was assessed under each individual cue and setting. The presence of the vibrotactile cue promoted a better performance than the force cue alone. This agreed with the applicability of tactile cues for sensing 3D surfaces, herein setting a baseline for using MLE. The task performance under the collocated setting indicated a degree of combining the individual cues. In contrast, the performance under the dislocated setting was alike under the individual vibrotactile cue. These observations imply a possible role of MLE in integrating force and vibrotactile cues for 3D user interaction within VEs.

2006 International Conference of the IEEE Engineering in Medicine and Biology Society, 2006

Study has shown that three-dimensional (3D) visualization of lung cavities has distinct advantage... more Study has shown that three-dimensional (3D) visualization of lung cavities has distinct advantages over traditional computed tomographic (CT) images for surgical planning. A crucial step for achieving 3D visualization of lung cavities is the segmentation of lung lobes by identifying lobar fissures in volumetric CT images. Current segmentation algorithms for lung lobes rely on manually placed markers to identify the fissures. This paper presents an autonomous algorithm that effectively segments the lung lobes without user intervention. This algorithm applies a two-stage approach: (a) adaptive fissure sweeping to coarsely define fissure regions of lobar fissures; and (b) watershed transform to refine the location and curvature of fissures within the fissure regions. We have tested this algorithm on 4 CT data sets. Comparing with visual inspection, the algorithm provides an accuracy of 85.5-95.0% and 88.2-92.3% for lobar fissures in the left and right lungs, respectively. This work proves the feasibility of developing an automatic algorithm for segmenting lung lobes.

2017 IEEE Symposium on 3D User Interfaces (3DUI), 2017

Proper integration of sensory cues facilitates 3D user interaction within virtual environments (V... more Proper integration of sensory cues facilitates 3D user interaction within virtual environments (VEs). Studies on multi-sensory integration of visual and haptic cues revealed that the integration follows maximum likelihood estimation (MLE). Little effort focuses however on integrating force and vibrotactile cues-two sub-categorical cues of the haptic modality. Hence, this paper presents an investigation on MLE's suitability for integrating these sub-categorical cues. Within a stereoscopic VE, human users performed a 3D interactive task of navigating a flying drone along a high-voltage transmission line in an inaccessible region and identifying defects on the line. The users had to identify defects via individual force or vibrotactile cues, and their combinations in colocated and dislocated settings. The co-located setting provided both cues on the right hand of the users; whereas the dislocated setting delivered the force and vibrotactile cues on the right hand and forearm of the users, respectively. Task performance of the users, such as completion time and accuracy, was assessed under each cue and setting. The presence of the vibrotactile cue promoted a better performance than the force cue alone. This was in agreement with the role of tactile cues in sensing surface properties, herein setting a baseline for using MLE. The task performance under the co-located setting indicated certain degrees of combining those under the individual cues. In contrast, the performance under the dislocated setting was alike that under the individual vibrotactile cue. These observations imply an inconclusiveness of MLE to integrate both cues in a co-located setting for 3D user interaction.

2019 IEEE Conference on Virtual Reality and 3D User Interfaces (VR), 2019

Current virtual environments (VE) enable perceiving haptic stimuli to facilitate 3D user interact... more Current virtual environments (VE) enable perceiving haptic stimuli to facilitate 3D user interaction, but lack brain-interfacial contents. Using electroencephalography (EEG), we undertook a feasibility study on exploring event-related potential (ERP) patterns of the user's brain responses during haptic interaction within a VE. The interaction was flying a virtual drone along a curved transmission line to detect defects under the stimuli (e.g., force increase and/or vibrotactile cues). We found that there were variations in the peak amplitudes and latencies (as ERP patterns) of the responses at about 200 ms post the onset of the stimuli. The largest negative peak occurred during 200~400 ms after the onset in all vibration-related blocks. Moreover, the amplitudes and latencies of the peak were differentiable among the vibration-related blocks. These findings imply feasible decoding of the brain responses during haptic interaction within VEs.

Journal of Visualization, 2019

Turbulent vortex shedding in the wake of a bluff body often contains cycle-to-cycle variations in... more Turbulent vortex shedding in the wake of a bluff body often contains cycle-to-cycle variations in the shape, trajectory, and intensity of vortices. Existing flow visualization techniques cannot effectively present these variations and, consequently, their influence on the aerodynamics to the user. This paper explores a new flow visualization approach to represent quasi-periodic vortex shedding over multiple shedding cycles concurrently. This approach uses a reduced-dimension representation of spatiotemporal vortex progression (called evolution surfaces) and ensemble visualization techniques (clustering). The resulting visualization can be used to identify topological changes in the behavior and strengths of coherent structures (i.e. vortices) in unsteady flows. This approach is applied in two case studies of bluff body wakes with Reynolds Numbers Re = 1200 (Hemmati et al. 2016c) and Re = 300 (Morton et al. 2018). In prior work, classification of these wakes' dynamics was based on energy fluctuation and shedding topology. However, these techniques are not well suited for representing characteristic changes between shedding regimes. In the present work, it has been shown that evolution surface clusters help to identify topological changes characterizing cycle-to-cycle variations in vortex behavior, while reducing visual clutter. The results indicate that evolution surface clusters are a promising visualization tool for comparative analysis of unsteady vortex dynamics in turbulent wakes.

Applied Sciences, 2017

Collaborative virtual environments (CVEs) present ways for human users to work together on a task... more Collaborative virtual environments (CVEs) present ways for human users to work together on a task. Research efforts of CVEs have mainly focused on the factors that affect the task performance of the users, such as awareness, communication, and presence. Furthermore, the users involved normally have the same task experience or knowledge background. In this paper, we examined the effect of interactive strategies for human/human interaction, which involves human users with different levels of expertise. Within a CVE for an expert and a novice, we deployed three interactive strategies-Tele-Operation, Tele-Assistance3, and Tele-Assistance7-to give the three degrees of autonomy to the novice. Focusing on the performance of the novice, our findings revealed that each interactive strategy has a different effect on the task performance of the novice. These findings could aid in choosing an optimal interactive strategy for performing a collaborative task between an expert and a novice.

2016 IEEE Symposium on 3D User Interfaces (3DUI), 2016

4 CONCLUSION AND FUTURE WORK This work revealed that the compass pattern yields better performanc... more 4 CONCLUSION AND FUTURE WORK This work revealed that the compass pattern yields better performance of navigation than the pushing pattern. This indicates a potential of using the compass pattern to facilitate navigation in VEs. Future work includes the refinement of the compass pattern for reducing cybersickness.

IEEE SMC'99 Conference Proceedings. 1999 IEEE International Conference on Systems, Man, and Cybernetics (Cat. No.99CH37028)

We conducted two experiments to compare the visual frames of reference used to scale grasping mov... more We conducted two experiments to compare the visual frames of reference used to scale grasping movements directed at objects with those used to estimate the size of the same objects-either immediately or after a 5-s delay. A virtual "workbench" was employed for presenting two different-sized objects in 3D. Subjects were instructed to pick up or estimate the marked one of the two objects. We found that the presence of the other object affected not only the estimate of the size of the target object when subjects made their estimates both immediately and after a 5-s delay, but also the scaling of grip aperture in flight when subjects picked up the target object after a 5-s delay. However, when subjects picked up the target object immediately, their grasp was scaled to the actual size of the target object and was not influenced by the presence of the other object. These findings suggest that the control of delayed motor actions utilizes the same relative metrics in allocentric frames of reference used by conscious perception, whereas the control of normal visually guided motor actions relies on absolute metrics in egocentric frames of reference. Implications of these findings for the design of human-machine interfaces are discussed.

Proceedings of the 9th IEEE International Conference on Collaborative Computing: Networking, Applications and Worksharing, 2013

Multiuser collaborative virtual environments (VEs) need strategies of conflict resolution to hand... more Multiuser collaborative virtual environments (VEs) need strategies of conflict resolution to handle simultaneous interaction with shared objects. Current strategies are first-comefirst-serve (FCFS) and predefined static priority of each user. These strategies cannot provide each user with a perceived equal opportunity of interaction and often lead to perceived unfairness to abandon collaboration. To offer an equal opportunity, we created a dynamic priority (DP) strategy and compared the strategy with the FCFS strategy based upon subjective perception of multiple users. Visual or haptic (pertinent to the sense of touch) cues assisted each user to perceive his/her gaining of interaction. We observed that the DP strategy yielded significantly an equal opportunity of interaction. The haptic cue offered lower variations in perceiving the equality than the visual cue under the DP strategy. These observations imply a potential application of the DP strategy in a VE, where various experts require equal opportunities in collaboration.

Canadian Journal of Surgery, 2013

Feasibility and fidelity of practising surgical fixation on a virtual ulna bone Background: Surgi... more Feasibility and fidelity of practising surgical fixation on a virtual ulna bone Background: Surgical simulators provide a safe environment to learn and practise psychomotor skills. A goal for these simulators is to achieve high levels of fidelity. The purpose of this study was to develop a reliable surgical simulator fidelity questionnaire and to assess whether a newly developed virtual haptic simulator for fixation of an ulna has comparable levels of fidelity as Sawbones. Methods: Simulator fidelity questionnaires were developed. We performed a stratified randomized study with surgical trainees. They performed fixation of the ulna using a virtual simulator and Sawbones. They completed the fidelity questionnaires after each procedure. Results: Twenty-two trainees participated in the study. The reliability of the fidelity questionnaire for each separate domain (environment, equipment, psychological) was Cronbach α greater than 0.70, except for virtual environment. The Sawbones had significantly higher levels of fidelity than the virtual simulator (p < 0.001) with a large effect size difference (Cohen d < 1.3). Conclusion: The newly developed fidelity questionnaire is a reliable tool that can potentially be used to determine the fidelity of other surgical simulators. Increasing the fidelity of this virtual simulator is required before its use as a training tool for surgical fixation. The virtual simulator brings with it the added benefits of repeated, independent safe use with immediate, objective feedback and the potential to alter the complexity of the skill. Contexte : Les simulateurs chirurgicaux offrent un environnement sécuritaire pour apprendre et pour exercer les habiletés psychomotrices. L'un des objectifs de ces simulateurs est de produire des degrés élevés de fidélité. Le but de cette étude était de mettre au point un questionnaire fiable sur la fidélité des simulateurs chirurgicaux et de vérifier si un nouveau simulateur virtuel, avec interface haptique, pour la fixation du cubitus présentait des taux de fidélité comparables à ceux du simulateur Sawbones. Méthodes : Des questionnaires sur la fidélité des simulateurs ont été préparés. Nous avons procédé à une étude randomisée stratifiée auprès de stagiaires en chirurgie qui ont effectué une fixation du cubitus à l'aide du simulateur virtuel et à l'aide du simulateur Sawbones. Ils ont répondu au questionnaire sur la fidélité après chaque intervention. Résultats : Vingt-deux stagiaires ont participé à l'étude. La fiabilité du questionnaire sur la fidélité pour chaque domaine distinct (environnement, équipement, dimension psychologique) correspondait à un coefficient α Cronbach supérieur à 0,70, sauf pour ce qui est de l'environnement virtuel. Le simulateur Sawbones a présenté des taux de fidélité significativement plus élevés que le simulateur virtuel (p < 0,001), avec une différence importante au plan de la taille de l'effet (indice d de Cohen < 1,3). Conclusion : Le nouveau questionnaire sur la fidélité s'est révélé un outil fiable qui peut servir à déterminer le degré de fidélité d'autres simulateurs chirurgicaux. Il faudra améliorer la fidélité de ce simulateur virtuel avant de pouvoir l'utiliser comme outil de formation pour la fixation chirurgicale. Ce simulateur virtuel a l'avantage de permettre des utilisations sécuritaires répétées et indépendantes avec des résultats immédiats et objectifs et de modifier la complexité de l'habileté. S urgical simulators provide a safe environment where a surgical trainee can learn and practise psychomotor skills. A goal for these simulators is to achieve high levels of fidelity so that they can be used in surgical curricula. The fidelity of a simulator is important, as it helps determine the extent to which a trainee is able to learn from the simulated experience and transfer the learning to the real environment. Fidelity can be defined as the

Fourth IEEE Conference on Cognitive Informatics, 2005. (ICCI 2005)., 2005

ABSTRACT

2011 IEEE World Haptics Conference, 2011

Virtual Reality (VR) technology has great potential as a tool for training. Remote haptic virtual... more Virtual Reality (VR) technology has great potential as a tool for training. Remote haptic virtual environments (VE) allow multiple users to interact in the same virtual space to accomplish tasks. Combining these ideas, it is possible to apply a remote VE to connect skilled trainers with remote trainees for training. In this paper we examined guided haptic training as an

Journal of Cognitive Neuroscience, 2000

We carried out three experiments designed to compare the effects of relative and absolute size on... more We carried out three experiments designed to compare the effects of relative and absolute size on manual prehension and manual estimates of perceived size. In each experiment, right-handed subjects were presented with two different-sized 3-D objects in a virtual display and were instructed to pick up or estimate the size of one of them. In Experiment 1, subjects were requested to pick up the smaller one of two virtual objects under one condition and the larger one under the other condition. In fact, the target object was identical on all trials; it was simply paired with a smaller object on some trials and a larger object on others. To provide veridical haptic feedback, a real object was positioned beneath a mirror at the same location as the virtual target object. In Experiment 2, one of the virtual objects was marked with a red dot on its top surface. From trial to trial, the marked object was paired with a larger, smaller, or same-sized object. Subjects were instructed to always ...

IEEE Transactions on Biomedical Engineering, 2009

Modernmultislice computed tomography (CT) scanners produce isotropic CT images with a thickness o... more Modernmultislice computed tomography (CT) scanners produce isotropic CT images with a thickness of 0.6 mm. These CT images offer detailed information of lung cavities, which could be used for better surgical planning of treating lung cancer. The major challenge for developing a surgical planning system is the automatic segmentation of lung lobes by identifying the lobar fissures. This paper presents a lobe segmentation algorithm that uses a twostage approach: 1) adaptive fissure sweeping to find fissure regions and 2) wavelet transform to identify the fissure locations and curvatures within these regions. Tested on isotropic CT image stacks from nine anonymous patients with pathological lungs, the algorithm yielded an accuracy of 76.7%-94.8% with strict evaluation criteria. In comparison, surgeons obtain an accuracy of 80% for localizing the fissure regions in clinical CT images with a thickness of 2.5-7.0 mm. As well, this paper describes a procedure for visualizing lung lobes in three dimensions using software-amira-and the segmentation algorithm. The procedure, including the segmentation, needed about 5 min for each patient. These results provide promising potential for developing an automatic algorithm to segment lung lobes for surgical planning of treating lung cancer.

Geoderma, 2010

For the investigation of many geometrical features of soils, computer-assisted image analysis has... more For the investigation of many geometrical features of soils, computer-assisted image analysis has become a method of choice over the last few decades. This analysis involves numerous steps, regarding which subjective decisions have to be made by the individuals conducting the research. This is particularly the case with the thresholding step, required to transform the original (color or greyscale) images into the type of binary representation (e.g., pores in white, solids in black) needed for fractal analysis or simulation with Lattice-Boltzmann models. Limited information exists at present on whether different observers, analyzing the same soil, would be likely to obtain similar results. In this general context, the first objective of the research reported in this article was to determine, through a so-called "round-robin" test, how much variation exists among the outcomes of various image thresholding strategies (including any image pretreatment deemed appropriate), routinely adopted by soil scientists. Three test imagesof a field soil, a soil thin section, and a virtual section through a 3-dimensional CT data setwere thresholded by 13 experts, worldwide. At the same time, variability of the outcomes of a set of automatic thresholding algorithms, applied to portions of the test images, was also investigated. The experimental results obtained illustrate the fact that experts rely on very different approaches to threshold images of soils, and that there is considerable observer influence associated with this thresholding. This observer dependence is not likely to be alleviated by adoption of one of the many existing automatic thresholding algorithms, many of which produce thresholded images that are equally, or even more, variable than those of the experts. These observations suggest that, at this point, analysis of the same image of a soil, be it a simple photograph or 3-dimensional X-ray CT data, by different individuals can lead to very different results, without any assurance that any of them would be even approximately "correct" or best suited to the objective at hand. Different strategies are proposed to cope with this situation, including the use of physical "standards", adoption of procedures to assess the accuracy of thresholding, benchmarking with physical measurements, or the development of computational methods that do not require binary images.

Experimental Brain Research, 2005

It has been repeatedly demonstrated that the opening between the index finger and thumb (grasp co... more It has been repeatedly demonstrated that the opening between the index finger and thumb (grasp component) during an object-directed reach-to-grasp movement achieves maximum aperture approximately two-thirds of the way through the duration of the reaching movement (transport component). Here we offer a quantitative model of the temporal coupling between grip aperture and wrist velocity which shows experimentally that the correlation between grip aperture and object size is a sigmoidal function of movement duration. When wrist velocity reaches its peak value, the correlation between the grip aperture and the size of the goal object has reached half of the correlation that is achieved by the end of the movement.

European Journal of Cardio-Thoracic Surgery, 2007

Objective: Three-dimensional (3D) displays of anatomic structures have become feasible for preope... more Objective: Three-dimensional (3D) displays of anatomic structures have become feasible for preoperative planning in some surgical procedures. There have been no reports, however, on the use of 3D displays for surgical treatment of lung cancer. We hypothesized that 3D displays of the thorax are useful for preoperative planning for lung cancer. Methods: Based on virtual reality technologies, we rendered 3D displays of the thorax from two-dimensional (2D) computed tomographic (CT) images of six anonymous patients, some of whom underwent surgical removal of lung cancer. For determining the resectability of lung cancer, we tested 17 participants with varying degrees of surgical skills to view 3D displays and read 2D CT images of these thoracic cavities in a randomized order. We measured their performance in terms of the accuracy of predicted resectability, the confidence of their prediction, planning time used, and workload experienced. Results: The results demonstrated that viewing 3D displays of thoracic cavities has significant advantages over reading 2D CT images in determining the resectability of lung cancer: increasing the accuracy of predicted resectability by about 20%, enhancing the confidence of the prediction by about 20%, decreasing planning time by about 30%, and reducing workload by about 50%. All participants preferred viewing 3D displays to reading 2D CT images for preoperative planning. Junior residents found 3D displays of thoraces more useful than senior residents. Conclusions: It is feasible to use 3D displays of the thorax for preoperative planning in treating lung cancer. Using 3D displays in surgical treatment of lung cancer has potential benefits, once the technique is perfected.

Biological Procedures Online, 2006

Microbes frequently live within multicellular, solid surface-attached assemblages termed biofilms... more Microbes frequently live within multicellular, solid surface-attached assemblages termed biofilms. These microbial communities have architectural features that contribute to population heterogeneity and consequently to emergent cell functions. Therefore, three-dimensional (3D) features of biofilm structure are important for understanding the physiology and ecology of these microbial systems. This paper details several protocols for scanning electron microscopy and confocal laser scanning microscopy (CLSM) of biofilms grown on polystyrene pegs in the Calgary Biofilm Device (CBD). Furthermore, a procedure is described for image processing of CLSM data stacks using amira™, a virtual reality tool, to create surface and/or volume rendered 3D visualizations of biofilm microorganisms. The combination of microscopy with microbial cultivation in the CBD-an apparatus that was designed for highthroughput susceptibility testing-allows for structure-function analysis of biofilms under multivariate growth and exposure conditions. Harrison et al.-The use of microscopy and three-dimensional visualization to evaluate the structure of microbial biofilms cultivated in the Calgary Biofilm Device www.biologicalprocedures.com

Biofouling, 2008

Quantitative parameters for describing the morphology of biofilms are crucial towards establishin... more Quantitative parameters for describing the morphology of biofilms are crucial towards establishing the influence of growing conditions on biofilm structure. Parameters used in earlier studies generally fail to differentiate complex three-dimensional structures. This article presents a novel approach of defining a parameter vector based on the energy signature of multi-resolution analysis, which was applied to differentiating biofilm structures from confocal laser scanning microscopy (CLSM) biofilm images. The parameter vector distinguished differences in the spatial arrangements of synthetic images. For real CLSM images, this parameter vector detected subtle differences in biofilm structure for three sample cases: (1) two adjacent images of a CLSM stack; (2) two partial stacks from the same CLSM stack with equal numbers of images but spatially offset by one image; and (3) three complete CLSM stacks from different bacterial strains. It was also observed that filtering the noise in CLSM images enhanced the sensitivity of the differentiation using our parameter vector.