Dissertation•
Linear and Angular Head Accelerations in Daily Life
29 Jul 2005-
TL;DR: It is suggested that the manuscript should be rewritten in a chapters-by- chapters format to facilitate more detailed discussion of the author's research and its findings.
Abstract: ......................................................................................................... ii Acknowledgements ...................................................................................... iv Table of
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11 Aug 2017
TL;DR: A novel ultra wide view based method to stream high quality VR on Internet at low bandwidth and little computation cost by splitting the source VR into small grid videos in advance to save bandwidth and expand the view that user requested to meet the real time interaction requirement.
Abstract: Online VR streaming faces great challenges such as the high throughput and real time interaction requirement. In this paper, we propose a novel ultra wide view based method to stream high quality VR on Internet at low bandwidth and little computation cost. First, we only transmit the region where user is looking at instead of full 360° view to save bandwidth. To achieve this goal, we split the source VR into small grid videos in advance. The grid videos are able to reconstruct any view flexibly in user end. Second, according to the fact that users generally interact at low speed, we expand the view that user requested to meet the real time interaction requirement. Besides, a low resolution full view stream is supplied to handle exceptional cases such as high speed view change. We test our solution in an experimental network. The results show remarkable bandwidth saving of over 60% in average at little computation cost while supplying the same quality of experience as local VR.
39 citations
Cites background from "Linear and Angular Head Acceleratio..."
...First, the angular speed of human’s view change is relatively low [3], which implies an expanded FoV streaming can relax the network delay effectively....
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TL;DR: A case study demonstrated that the measurement of the shaking and nodding angles, produced from the proposed system, can effectively characterise the drivers’ behaviour while engaged in the NDAs of chatting to a passenger and playing on a smartphone.
Abstract: Although at present legislation does not allow drivers in a Level 3 autonomous vehicle to engage in a secondary task, there may become a time when it does. Monitoring the behaviour of drivers engaging in various non-driving activities (NDAs) is crucial to decide how well the driver will be able to take over control of the vehicle. One limitation of the commonly used face-based head tracking system, using cameras, is that sufficient features of the face must be visible, which limits the detectable angle of head movement and thereby measurable NDAs, unless multiple cameras are used. This paper proposes a novel orientation sensor based head tracking system that includes twin devices, one of which measures the movement of the vehicle while the other measures the absolute movement of the head. Measurement error in the shaking and nodding axes were less than 0.4°, while error in the rolling axis was less than 2°. Comparison with a camera-based system, through in-house tests and on-road tests, showed that the main advantage of the proposed system is the ability to detect angles larger than 20° in the shaking and nodding axes. Finally, a case study demonstrated that the measurement of the shaking and nodding angles, produced from the proposed system, can effectively characterise the drivers' behaviour while engaged in the NDAs of chatting to a passenger and playing on a smartphone.
23 citations
Cites background from "Linear and Angular Head Acceleratio..."
...The speed of rotation was chosen to be 30◦/s, which is about four times slower than the average movement expected in non-driving tasks [31]....
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...The speed of rotation was chosen to be 30°/s, which is about four times slower than the average movement expected in non-driving tasks [31]....
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31 Mar 2020
TL;DR: The concerns, current practice, and limitations for capturing, reconstructing, and representing the real world visually within virtual reality, and several promising directions for future work to improve the quality and flexibility of real-world VR capture systems are outlined.
Abstract: We provide an overview of the concerns, current practice, and limitations for capturing, reconstructing, and representing the real world visually within virtual reality. Given that our goals are to capture, transmit, and depict complex real-world phenomena to humans, these challenges cover the opto-electro-mechanical, computational, informational, and perceptual fields. Practically producing a system for real-world VR capture requires navigating a complex design space and pushing the state of the art in each of these areas. As such, we outline several promising directions for future work to improve the quality and flexibility of real-world VR capture systems.
15 citations
17 Oct 2019
TL;DR: This paper introduces gated clips which do not play the video past a gate time until a filmmaker-defined viewer gaze condition is met, such as looking at a specific region of interest (ROI).
Abstract: A major concern for filmmakers creating 360° video is ensuring that the viewer does not miss important narrative elements because they are looking in the wrong direction. This paper introduces gated clips which do not play the video past a gate time until a filmmaker-defined viewer gaze condition is met, such as looking at a specific region of interest (ROI). Until the condition is met, we seamlessly loop video playback using view-dependent video textures, a new variant of standard video textures that adapt the looping behavior to the portion of the scene that is within the viewer's field of view. We use our desktop GUI to edit live action and computer animated 360° videos. In a user study with casual viewers, participants prefer our looping videos over the standard versions and are able to successfully see all of the looping videos' ROIs without fear of missing important narrative content.
12 citations
Cites methods from "Linear and Angular Head Acceleratio..."
...Based on the work of Bussone [10], we assume a typical maximum head velocity movement of 9....
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...Based on the work of Bussone [10], we assume a typical maximum head velocity movement of 9.03 rad/s....
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TL;DR: The purpose of this study was to evaluate the literature investigating head kinematics associated with everyday activities and to generate a comprehensive kinematic boundary envelope describing these motions and determine the current state of published knowledge regarding ‘normally occurring’ head accelerations.
Abstract: Various studies have characterized head kinematics in specific everyday activities by looking at linear and/or rotational acceleration characteristics, but each has evaluated a limited number of activities. Furthermore, these studies often present dissimilar and sometimes incomplete descriptions of the resulting kinematics, so the characteristics of normal everyday activities as a whole are not easily collectively summarized. The purpose of this study was to evaluate the literature investigating head kinematics associated with everyday activities and to generate a comprehensive kinematic boundary envelope describing these motions. The envelope constructed constitutes the current state of published knowledge regarding ‘normally occurring’ head accelerations. The envelope of kinematics represents activities commonly encountered and posing zero to minimal risk of injury to healthy individuals. Several kinematic measures, including linear accelerations, rotational velocities, and rotational accelerations, one may encounter as a result of normal everyday activities are summarized. A total of 11 studies encompassing 49 unique activities were evaluated. Examples of activities include sitting in a chair, jumping off a step, running, and walking. The peak resultant linear accelerations of the head reported in the literature were all less than 15 g, while the peak resultant rotational accelerations and rotational velocities approach 1375 rad/s2 and 12.8 rad/s, respectively. The resulting design envelope can be used to understand the range of acceleration magnitudes a typical active person can expect to experience. The results are also useful to compare to other activities exposing the head to motion or impact including sports, military, automotive, aerospace and other sub-injurious and injurious events.
11 citations
References
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01 Jul 1955
1,185 citations
"Linear and Angular Head Acceleratio..." refers background in this paper
...He also describes it as a point in the sphenoid sinus, 4 mm beyond the anteroinferior margin of the sella turcica (Dempster 1955)....
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01 Aug 1969
TL;DR: Weight, volume, and center of mass of 14 segments of the body were determined on 13 male cadavers and descriptive statistics of these variables as well as a series of regression equations predicting these parameters from anthropometry are presented.
Abstract: : This study was designed to supplement existing knowledge of the weight, volume, and center of mass of segments of the human body and to permit their more accurate estimation on the living from anthropometric dimensions. Weight, volume, and center of mass of 14 segments of the body were determined on 13 male cadavers. Presented are descriptive statistics of these variables as well as a series of regression equations predicting these parameters from anthropometry. Included in the seven supporting appendices are reports of studies of the mid-volume of segments as an approximation of their center of mass, relationships between standing and supine anthropometry, postmortem changes in gross body size, and comparisons between densities of fresh and preserved human tissues.
1,041 citations
"Linear and Angular Head Acceleratio..." refers background in this paper
...Dempster WT. (1955) Space requirements of the seated operator....
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TL;DR: In this study, an attempt is made to delineate actual injury causation and establish a meaningful injury criterion through the use of the actual field accident data to establish the new brain injury tolerance level.
Abstract: Traumatic brain injuries constitute a significant portion of injury resulting from automotive collisions, motorcycle crashes, and sports collisions. Brain injuries not only represent a serious trauma for those involved but also place an enormous burden on society, often exacting a heavy economical, social, and emotional price. Development of intervention strategies to prevent or minimize these injuries requires a complete understanding of injury mechanisms, response and tolerance level. In this study, an attempt is made to delineate actual injury causation and establish a meaningful injury criterion through the use of the actual field accident data. Twenty-four head-to-head field collisions that occurred in professional football games were duplicated using a validated finite element human head model. The injury predictors and injury levels were analyzed based on resulting brain tissue responses and were correlated with the site and occurrence of mild traumatic brain injury (MTBI). Predictions indicated that the shear stress around the brainstem region could be an injury predictor for concussion. Statistical analyses were performed to establish the new brain injury tolerance level.
883 citations
TL;DR: Concussion occurs with considerable head impact velocity and velocity changes in professional football, primarily related to translational acceleration resulting from impacts on the facemask or side, or falls on the back of the helmet.
Abstract: Objective Concussion in professional football was studied with respect to impact types and injury biomechanics. A combination of video surveillance and laboratory reconstruction of game impacts was used to evaluate concussion biomechanics. Methods Between 1996 and 2001, videotapes of concussions and significant head impacts were collected from National Football League games. There were clear views of the direction and location of the helmet impact for 182 cases. In 31 cases, the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted Hybrid III dummies and the same impact velocity, direction, and head kinematics as in the game. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studies were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used. Results Concussed players experienced head impacts of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 miles/h). There was a rapid change in head velocity of 7.2 +/- 1.8 m/s (16.1 +/- 4.0 miles/h), which was significantly greater than that for uninjured struck players (5.0 +/- 1.1 m/s, 11.2 +/- 2.5 miles/h; t = 2.9, P Conclusion Concussion occurs with considerable head impact velocity and velocity changes in professional football. Current National Operating Committee on Standards for Athletic Equipment standards primarily address impacts to the periphery and crown of the helmet, whereas players are experiencing injuries in impacts to the facemask, side, and back of the helmet. New tests are needed to assess the performance of helmets in reducing concussion risks involving high-velocity and long-duration injury biomechanics.
586 citations
TL;DR: Findings suggest that one of the primary objectives of the postural control system when walking on irregular surfaces is head control, and that subjects adapt their stepping pattern on irregular surface to ensure that the head remains stable.
574 citations
"Linear and Angular Head Acceleratio..." refers background in this paper
...Woodman and Menz both agreed with those numbers, but Woodman found an anterior-posterior acceleration of 0.5 g. Angular accelerations were also recorded by Woodman, with approximately 40 rad/s2 in pitch and 10 rad/s2 in both roll and yaw (Woodman and Griffin 1996, Menz et al 2002)....
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