Browsing by Author "Kopper, Regis"
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Item Open Access Evaluating the effects of image persistence on dynamic target acquisition in low frame rate virtual environments(2016 IEEE Symposium on 3D User Interfaces, 3DUI 2016 - Proceedings, 2016-04-26) Zielinski, David J; Rao, Hrishikesh M; Potter, Nicholas D; Sommer, Marc A; Appelbaum, Lawrence G; Kopper, Regis© 2016 IEEE.User performance in virtual environments with degraded visual conditions due to low frame rates is an interesting area of inquiry. Visual content shown in a low frame rate simulation has the quality of the original image, but persists for an extended period until the next frame is displayed (so-called high persistence-HP). An alternative, called low persistence (LP), involves displaying the rendered frame for a single display frame and blanking the screen while waiting for the next frame to be generated. Previous research has evaluated the usefulness of the LP technique in low frame rate simulations during a static target acquisition task. To gain greater knowledge about the LP technique, we have conducted a user study to evaluate user performance and learning during a dynamic target acquisition task. The acquisition task was evaluated under a high frame rate, (60 fps) condition, a traditional low frame rate HP condition (10 fps), and the experimental low frame rate LP technique. The task involved the acquisition of targets moving along several different trajectories, modeled after a shotgun trap shooting task. The results of our study indicate the LP condition approaches high frame rate performance within certain classes of target trajectories. Interestingly we also see that learning is consistent across conditions, indicating that it may not always be necessary to train under a visually high frame rate system to learn a particular task. We discuss implications of using the LP technique to mitigate low frame rate issues as well as its potential usefulness for training in low frame rate virtual environments.Item Open Access Evaluation of an Eye Tracking Selection Technique with Progressive Refinement(2018) Wang, YunhanWe designed a novel eye tracking selection technique with progressive refinement - eye-controlled sphere-casting refined by quad-menu (EyeSQUAD) selection technique. Through a user study, we evaluated the performance of this technique with comparison of two previous selection techniques - ray-casting and SQUAD under different target size and distractor density scenarios. Results show that the EyeSQUAD technique can achieve similar selection speed as ray-casting and SQUAD and is more accurate than ray-casting although less precise than SQUAD. Finally, we summarized several insights for designing interaction techniques with eye tracking.
Item Open Access Exploring the effects of image persistence in low frame rate virtual environments(2015 IEEE Virtual Reality Conference, VR 2015 - Proceedings, 2015-08-25) Zielinski, David J; Rao, Hrishikesh M; Sommer, Marc A; Kopper, Regis© 2015 IEEE.In virtual reality applications, there is an aim to provide real time graphics which run at high refresh rates. However, there are many situations in which this is not possible due to simulation or rendering issues. When running at low frame rates, several aspects of the user experience are affected. For example, each frame is displayed for an extended period of time, causing a high persistence image artifact. The effect of this artifact is that movement may lose continuity, and the image jumps from one frame to another. In this paper, we discuss our initial exploration of the effects of high persistence frames caused by low refresh rates and compare it to high frame rates and to a technique we developed to mitigate the effects of low frame rates. In this technique, the low frame rate simulation images are displayed with low persistence by blanking out the display during the extra time such image would be displayed. In order to isolate the visual effects, we constructed a simulator for low and high persistence displays that does not affect input latency. A controlled user study comparing the three conditions for the tasks of 3D selection and navigation was conducted. Results indicate that the low persistence display technique may not negatively impact user experience or performance as compared to the high persistence case. Directions for future work on the use of low persistence displays for low frame rate situations are discussed.Item Open Access Granulated rest frames as a technique to mitigate visually-induced motion sickness and their application(2022) Cao, ZekunAs a visual cue, rest-frames are isotropically vertical and relatively stationary to subjects; they are used to alleviate visually induced motion sickness in the virtual reality experience. However, the use of rest-frames as a visually induced motion sickness–alleviation technique poses several challenges for the user. This is primarily because the existing design is content-based, not graphics-driver-level, so it cannot be seamlessly applied to various platforms. The design also blocks some peripheral vision, sacrificing the user’s spatial-recognition ability.
This dissertation aims to understand and improve rest-frames’ design, making their use a viable technique to reduce visually induced motion sickness. This technique is graphics-driver-level, so it can run seamlessly in any environment. With this goal, the dissertation proposes and validates a novel design of rest-frames inspired by amodal completion: granulated rest-frames. A generic method to process stereoscopic videos to study user-experience is also presented. The new design implements rest-frames as visual noise with changeable settings to maintain the user’s spatial-recognition ability and provide more flexibility at the graphics-driver level.
This study finds the optimal size and sparsity of granulated rest-frames by investigating the user’s visual-search performance at different settings. It also validates the effect of granulated rest-frames in alleviating visually induced motion sickness in interactive virtual environments. The main finding is that granulated rest-frames can help first-time users adapt to a virtual environment more quickly without affecting the spatial-recognition ability of their peripheral vision. This dissertation also demonstrates the applicability of granulated rest-frames in stereoscopic videos in a preliminary study, as part of which a generic method to investigate users’ reactions to 360° videos is proposed. The dissertation also offers an experimental design to explore the utilization of granulated rest-frames’ effects in general-purpose interaction techniques in a future study.
Item Open Access Sensorimotor learning during a marksmanship task in immersive virtual reality(Frontiers in Psychology, 2018-02-06) Rao, Hrishikesh; Khanna, Rajan; Zielinski, David; Lu, Yvonne; Clements, Jillian; Potter, Nicholas; Sommer, MA; Kopper, Regis; Appelbaum, LawrenceSensorimotor learning refers to improvements that occur through practice in the performance of sensory-guided motor behaviors. Leveraging novel technical capabilities of an immersive virtual environment, we probed the component kinematic processes that mediate sensorimotor learning. Twenty naïve subjects performed a simulated marksmanship task modeled after Olympic Trap Shooting standards. We measured movement kinematics and shooting performance as participants practiced 350 trials while receiving trial-by-trial feedback about shooting success. Spatiotemporal analysis of motion tracking elucidated the ballistic and refinement phases of hand movements. We found systematic changes in movement kinematics that accompanied improvements in shot accuracy during training, though reaction and response times did not change over blocks. In particular, we observed longer, slower, and more precise ballistic movements that replaced effort spent on corrections and refinement. Collectively, these results leverage developments in immersive virtual reality technology to quantify and compare the kinematics of movement during early learning of full body sensorimotor orienting.Item Open Access Sensorimotor learning during a marksmanship task in immersive virtual reality(Frontiers in Psychology, 2018-02-06) Rao, Hrishikesh M; Khanna, Rajan; Zielinski, David J; Lu, Yvonne; Clements, Jillian M; Potter, Nicholas D; Sommer, Marc A; Kopper, Regis; Appelbaum, L GregorySensorimotor learning refers to improvements that occur through practice in the performance of sensory-guided motor behaviors. Leveraging novel technical capabilities of an immersive virtual environment, we probed the component kinematic processes that mediate sensorimotor learning. Twenty naïve subjects performed a simulated marksmanship task modeled after Olympic Trap Shooting standards. We measured movement kinematics and shooting performance as participants practiced 350 trials while receiving trial-by-trial feedback about shooting success. Spatiotemporal analysis of motion tracking elucidated the ballistic and refinement phases of hand movements. We found systematic changes in movement kinematics that accompanied improvements in shot accuracy during training, though reaction and response times did not change over blocks. In particular, we observed longer, slower, and more precise ballistic movements that replaced effort spent on corrections and refinement. Collectively, these results leverage developments in immersive virtual reality technology to quantify and compare the kinematics of movement during early learning of full body sensorimotor orienting.Item Open Access The effect of rest frames on simulator sickness reduction(2017) Cao, ZekunWith increasing prevalence and capabilities of Virtual Reality (VR) as a part of education, entertainment, data analysis and industrial applications, the consideration of constructing a more user-friendly virtual environment becomes more important, which requires the reduction or elimination of simulator sickness (SS) -- a discomfort caused in simulated environment. As a form of motion sickness (MS) -- caused by movement in travel, some signs and symptoms of SS are the same as those of MS's, such as pallor, cold sweating, nausea, and vomiting. Several convincing theories or hypothesis to explain the cause of SS have been advanced, such as Sensory Conflict Theory, Postural Instability Theory and Rest Frames Hypothesis. Based on the first two theories aforementioned, high-quality tracking systems and modification of field of view (FOV) have been proposed to reduce the mismatch between visual perception and vestibular system in virtual environment (VE). Two main drawbacks exist in these techniques: (1) They will make uses weary in VE needs long distance physical navigation; (2) Modifying the field of view will decrease immersion.
To this end, inspired by the rest frame hypothesis and previous study on field of view, the goal of this research is to evaluate the effect of rest frames -- portions of the virtual environment that remain fixed in relation to the real world and do not move as the user moves around -- on SS reduction. A study was performed in this research, in which all participants experienced two different VR sessions: one with rest frames and the other without rest frames. The rest frames were developed by using a transparent cockpit attached with a black metal net in our experimental environment. A questionnaire asking users' discomfort was shown periodically in the VE during the study, which allowed us to record the level of participants' comfort in real time. Participants were required to finish a Simulator Sickness Questionnaire (SSQ) and a presence questionnaire after completing either session, to analyze the influence of rest frames on presence and their overall sickness induced by VR. Through comparing the time spent in VE, the real-time subjects' discomfort levels and scores of SSQ and presence questionnaire from both sessions, we found that rest frames have advantages as follows:
(1) Users could experience VEs without physical navigation;
(2) Rest frames significantly helped users acclimate to VR;
(3) The level of discomfort in VR was reduced;
(4) The level of presence was not impacted.
Item Open Access Wireless, Web-Based Interactive Control of Optical Coherence Tomography with Mobile Devices.(Transl Vis Sci Technol, 2017-01) Mehta, Rajvi; Nankivil, Derek; Zielinski, David J; Waterman, Gar; Keller, Brenton; Limkakeng, Alexander T; Kopper, Regis; Izatt, Joseph A; Kuo, Anthony NPURPOSE: Optical coherence tomography (OCT) is widely used in ophthalmology clinics and has potential for more general medical settings and remote diagnostics. In anticipation of remote applications, we developed wireless interactive control of an OCT system using mobile devices. METHODS: A web-based user interface (WebUI) was developed to interact with a handheld OCT system. The WebUI consisted of key OCT displays and controls ported to a webpage using HTML and JavaScript. Client-server relationships were created between the WebUI and the OCT system computer. The WebUI was accessed on a cellular phone mounted to the handheld OCT probe to wirelessly control the OCT system. Twenty subjects were imaged using the WebUI to assess the system. System latency was measured using different connection types (wireless 802.11n only, wireless to remote virtual private network [VPN], and cellular). RESULTS: Using a cellular phone, the WebUI was successfully used to capture posterior eye OCT images in all subjects. Simultaneous interactivity by a remote user on a laptop was also demonstrated. On average, use of the WebUI added only 58, 95, and 170 ms to the system latency using wireless only, wireless to VPN, and cellular connections, respectively. Qualitatively, operator usage was not affected. CONCLUSIONS: Using a WebUI, we demonstrated wireless and remote control of an OCT system with mobile devices. TRANSLATIONAL RELEVANCE: The web and open source software tools used in this project make it possible for any mobile device to potentially control an OCT system through a WebUI. This platform can be a basis for remote, teleophthalmology applications using OCT.