A Method of Generating Swept Volume From Motion Captured With Depth Sensors Using an Open Source Graphic System

2016 ◽  
Author(s):  
Jian Wan ◽  
Nanxin Wang ◽  
Robert Pakko
Keyword(s):  
Open Source ◽  
The Body ◽  
Microsoft Kinect ◽  
Body Motion ◽  
Automotive Application ◽  
Whole Body ◽  
Graphic System ◽  
Skeleton Model ◽  
Depth Sensors ◽  
Swept Volumes

One of the common usages of a captured human body motion in automotive application is creating swept volumes of the body surfaces based on the trajectories of its motion. Recent development of depth sensors enables fast and natural motion capture without attaching markers on subjects’ bodies. Microsoft Kinect is one of widely used depth sensors. It can track a whole body motion and output a skeleton model. A new method is developed to create the swept volumes from the motion captured by Kinect using an open source graphic system. The skeleton motion is recorded in a file format that is flexible to retain the skeleton’s structure and acceptable to various graphic systems. The motion is then bound with a surface manikin model in the graphic system, where the swept volumes are generated. This method is more flexible and portable than utilizing a commercial digital manikin, and potentially provides more accurate result.

scholarly journals Responses of Anterior Superior Temporal Polysensory (STPa) Neurons to “Biological Motion” Stimuli

1994 ◽  
Vol 6 (2) ◽  
pp. 99-116 ◽  
Author(s):  
M. W. Oram ◽  
D. I. Perrett
Keyword(s):  
Biological Motion ◽  
Temporal Cortex ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Global Pattern ◽  
Lighting Conditions ◽  
Specific Direction ◽  
Direction Of Movement ◽  
Light Stimuli

Cells have been found in the superior temporal polysensory area (STPa) of the macaque temporal cortex that are selectively responsive to the sight of particular whole body movements (e.g., walking) under normal lighting. These cells typically discriminate the direction of walking and the view of the body (e.g., left profile walking left). We investigated the extent to which these cells are responsive under “biological motion” conditions where the form of the body is defined only by the movement of light patches attached to the points of limb articulation. One-third of the cells (25/72) selective for the form and motion of walking bodies showed sensitivity to the moving light displays. Seven of these cells showed only partial sensitivity to form from motion, in so far as the cells responded more to moving light displays than to moving controls but failed to discriminate body view. These seven cells exhibited directional selectivity. Eighteen cells showed statistical discrimination for both direction of movement and body view under biological motion conditions. Most of these cells showed reduced responses to the impoverished moving light stimuli compared to full light conditions. The 18 cells were thus sensitive to detailed form information (body view) from the pattern of articulating motion. Cellular processing of the global pattern of articulation was indicated by the observations that none of these cells were found sensitive to movement of individual limbs and that jumbling the pattern of moving limbs reduced response magnitude. A further 10 cells were tested for sensitivity to moving light displays of whole body actions other than walking. Of these cells 5/10 showed selectivity for form displayed by biological motion stimuli that paralleled the selectivity under normal lighting conditions. The cell responses thus provide direct evidence for neural mechanisms computing form from nonrigid motion. The selectivity of the cells was for body view, specific direction, and specific type of body motion presented by moving light displays and is not predicted by many current computational approaches to the extraction of form from motion.

scholarly journals Perception of the dynamic visual vertical during sinusoidal linear motion

2017 ◽  
Vol 118 (4) ◽  
pp. 2499-2506 ◽  
Author(s):  
A. Pomante ◽  
L. P. J. Selen ◽  
W. P. Medendorp
Keyword(s):  
Vestibular System ◽  
Spatial Orientation ◽  
Linear Acceleration ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Linear Motion ◽  
Modeling Framework ◽  
Visual Vertical ◽  
The Brain

The vestibular system provides information for spatial orientation. However, this information is ambiguous: because the otoliths sense the gravitoinertial force, they cannot distinguish gravitational and inertial components. As a consequence, prolonged linear acceleration of the head can be interpreted as tilt, referred to as the somatogravic effect. Previous modeling work suggests that the brain disambiguates the otolith signal according to the rules of Bayesian inference, combining noisy canal cues with the a priori assumption that prolonged linear accelerations are unlikely. Within this modeling framework the noise of the vestibular signals affects the dynamic characteristics of the tilt percept during linear whole-body motion. To test this prediction, we devised a novel paradigm to psychometrically characterize the dynamic visual vertical—as a proxy for the tilt percept—during passive sinusoidal linear motion along the interaural axis (0.33 Hz motion frequency, 1.75 m/s2peak acceleration, 80 cm displacement). While subjects ( n=10) kept fixation on a central body-fixed light, a line was briefly flashed (5 ms) at different phases of the motion, the orientation of which had to be judged relative to gravity. Consistent with the model’s prediction, subjects showed a phase-dependent modulation of the dynamic visual vertical, with a subject-specific phase shift with respect to the imposed acceleration signal. The magnitude of this modulation was smaller than predicted, suggesting a contribution of nonvestibular signals to the dynamic visual vertical. Despite their dampening effect, our findings may point to a link between the noise components in the vestibular system and the characteristics of dynamic visual vertical.NEW & NOTEWORTHY A fundamental question in neuroscience is how the brain processes vestibular signals to infer the orientation of the body and objects in space. We show that, under sinusoidal linear motion, systematic error patterns appear in the disambiguation of linear acceleration and spatial orientation. We discuss the dynamics of these illusory percepts in terms of a dynamic Bayesian model that combines uncertainty in the vestibular signals with priors based on the natural statistics of head motion.

scholarly journals Transformation of vestibular signals for the decisions of hand choice during whole body motion

2019 ◽  
Vol 121 (6) ◽  
pp. 2392-2400 ◽  
Author(s):  
Romy S. Bakker ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
Reference Frame ◽  
Early Stage ◽  
Hand Preference ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Head Orientation ◽  
Inertial Acceleration ◽  
Reach Planning ◽  
The Brain

In daily life, we frequently reach toward objects while our body is in motion. We have recently shown that body accelerations influence the decision of which hand to use for the reach, possibly by modulating the body-centered computations of the expected reach costs. However, head orientation relative to the body was not manipulated, and hence it remains unclear whether vestibular signals contribute in their head-based sensory frame or in a transformed body-centered reference frame to these cost calculations. To test this, subjects performed a preferential reaching task to targets at various directions while they were sinusoidally translated along the lateral body axis, with their head either aligned with the body (straight ahead) or rotated 18° to the left. As a measure of hand preference, we determined the target direction that resulted in equiprobable right/left-hand choices. Results show that head orientation affects this balanced target angle when the body is stationary but does not further modulate hand preference when the body is in motion. Furthermore, reaction and movement times were larger for reaches to the balanced target angle, resembling a competitive selection process, and were modulated by head orientation when the body was stationary. During body translation, reaction and movement times depended on the phase of the motion, but this phase-dependent modulation had no interaction with head orientation. We conclude that the brain transforms vestibular signals to body-centered coordinates at the early stage of reach planning, when the decision of hand choice is computed. NEW & NOTEWORTHY The brain takes inertial acceleration into account in computing the anticipated biomechanical costs that guide hand selection during whole body motion. Whereas these costs are defined in a body-centered, muscle-based reference frame, the otoliths detect the inertial acceleration in head-centered coordinates. By systematically manipulating head position relative to the body, we show that the brain transforms otolith signals into body-centered coordinates at an early stage of reach planning, i.e., before the decision of hand choice is computed.

HUMAN POSTURE RECONSTRUCTION AND ANIMATION FROM MONOCULAR IMAGES BASED ON GENETIC ALGORITHMS

2005 ◽  
Vol 05 (02) ◽  
pp. 371-395
Author(s):  
JIANHUI ZHAO ◽  
LING LI ◽  
KWOH CHEE KEONG
Keyword(s):  
Genetic Algorithms ◽  
The Body ◽  
Human Model ◽  
Whole Body ◽  
Video Sequences ◽  
Body Parts ◽  
Criterion Function ◽  
Skeleton Model ◽  
Human Posture ◽  
Monocular Image

The paper aims to propose a new approach towards human posture reconstruction and animation from monocular video sequences that contain any kind of human postures and movements. This is a way towards low cost motion capture and at the same time it avoids many limitations of those classical methods. A parameterized human skeleton model based on anatomy is adopted where the angular constraints are encoded in the joints. Criterion Function is defined to represent the residuals between feature points in the monocular image and the corresponding points resulted from projecting the human model to the projection plane. By transforming each segment of the human model to achieve the minimum value of the Criterion Function, the proper human posture that resembles the one represented by the monocular image can be generated. Different kinds of adjustments are utilized to adjust the body parts into the proper locations and orientations in 3D space without camera calibration. In order to find the optimal solution effectively in a high-dimensional parameter space by considering all the parameters simultaneously, the method of Genetic Algorithms is proposed. A procedure is developed to recover the whole body posture, and then a human animation system is developed to animate a series of human movements from monocular image sequences, during which information between consecutive frames is considered to improve the accuracy. Our technique makes it feasible to reconstruct any possible human postures, and experimental results from many monocular images and video sequences are encouraging.

scholarly journals Distinct Representations of Body and Head motion are Dynamically Encoded by Purkinje cell Populations in the Macaque Cerebellum

2021 ◽  
Author(s):  
Omid A Zobeiri ◽  
Kathleen E Cullen
Keyword(s):  
Postural Control ◽  
Purkinje Cells ◽  
Body Position ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Head Motion ◽  
Response Dynamics ◽  
Dynamic Representation ◽  
Self Motion

The ability to accurately control our posture and perceive spatial orientation during self-motion requires knowledge of the motion of both the head and body. However, whereas the vestibular sensors and nuclei directly encode head motion, no sensors directly encode body motion. Instead, the integration of vestibular and neck proprioceptive inputs is necessary to transform vestibular information into the body-centric reference frame required for postural control. The anterior vermis of the cerebellum is thought to play a key role in this transformation, yet how its Purkinje cells integrate these inputs or what information they dynamically encode during self-motion remains unknown. Here we recorded the activity of individual anterior vermis Purkinje cells in alert monkeys during passively applied whole-body, body-under-head, and head-on-body rotations. Most neurons dynamically encoded an intermediate representation of self-motion between head and body motion. Notably, these neurons responded to both vestibular and neck proprioceptive stimulation and showed considerable heterogeneity in their response dynamics. Furthermore, their vestibular responses demonstrated tuning in response to changes in head-on-body position. In contrast, a small remaining percentage of neurons sensitive only to vestibular stimulation unambiguously encoded head-in-space motion across conditions. Using a simple population model, we establish that combining responses from 40 Purkinje cells can explain the responses of their target neurons in deep cerebellar nuclei across all self-motion conditions. We propose that the observed heterogeneity in Purkinje cells underlies the cerebellum's capacity to compute the dynamic representation of body motion required to ensure accurate postural control and perceptual stability in our daily lives.

scholarly journals Study of Postural Stability Features by Using Kinect Depth Sensors to Assess Body Joint Coordination Patterns

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1291
Author(s):  
Chin-Hsuan Liu ◽  
Posen Lee ◽  
Yen-Lin Chen ◽  
Chen-Wen Yen ◽  
Chao-Wei Yu
Keyword(s):  
Balance Control ◽  
The Body ◽  
Global Perspective ◽  
Microsoft Kinect ◽  
Coordination Pattern ◽  
Depth Sensor ◽  
Velocity Signal ◽  
Joint Coordination ◽  
Depth Sensors ◽  
Joint Velocity

A stable posture requires the coordination of multiple joints of the body. This coordination of the multiple joints of the human body to maintain a stable posture is a subject of research. The number of degrees of freedom (DOFs) of the human motor system is considerably larger than the DOFs required for posture balance. The manner of managing this redundancy by the central nervous system remains unclear. To understand this phenomenon, in this study, three local inter-joint coordination pattern (IJCP) features were introduced to characterize the strength, changing velocity, and complexity of the inter-joint couplings by computing the correlation coefficients between joint velocity signal pairs. In addition, for quantifying the complexity of IJCPs from a global perspective, another set of IJCP features was introduced by performing principal component analysis on all joint velocity signals. A Microsoft Kinect depth sensor was used to acquire the motion of 15 joints of the body. The efficacy of the proposed features was tested using the captured motions of two age groups (18–24 and 65–73 years) when standing still. With regard to the redundant DOFs of the joints of the body, the experimental results suggested that an inter-joint coordination strategy intermediate to that of the two extreme coordination modes of total joint dependence and independence is used by the body. In addition, comparative statistical results of the proposed features proved that aging increases the coupling strength, decreases the changing velocity, and reduces the complexity of the IJCPs. These results also suggested that with aging, the balance strategy tends to be more joint dependent. Because of the simplicity of the proposed features and the affordability of the easy-to-use Kinect depth sensor, such an assembly can be used to collect large amounts of data to explore the potential of the proposed features in assessing the performance of the human balance control system.

scholarly journals Rigid Foot Soles Improve Balance in Beam Walking

2019 ◽  
Author(s):  
Meghan E. Huber ◽  
Enrico Chiovetto ◽  
Martin Giese ◽  
Dagmar Sternad
Keyword(s):  
Degrees Of Freedom ◽  
Motor Task ◽  
Beam Width ◽  
Mechanical Effect ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Support Surface ◽  
Narrow Beam ◽  
Skill Levels

ABSTRACTMaintaining balance while walking on a narrow beam is a challenging motor task. This is presumably because the foot’s ability to exert torque on the support surface is limited by the beam width. Still, the feet serve as a critical interface between the body and the external environment, and it is unclear how the mechanical properties of the feet affect balance. Here we examined how restricting the degrees of freedom of the feet influenced balance behavior during beam walking. We recorded whole-body joint kinematics of subjects with varying skill levels as they walked on a narrow beam with and without wearing flat, rigid soles on their feet. We computed changes in whole-body motion and angular momentum across these conditions. Results showed that wearing rigid soles improved balance in the beam walking task, but that practice with rigid soles did not affect or transfer to task performance with bare feet. The absence of any after-effect suggested that the improved balance from constraining the foot was the result of a mechanical effect rather than a change in neural strategy. Though wearing rigid soles can be used to assist balance, there appear to be limited training or rehabilitation benefits from wearing rigid soles.

Infiltration of a Fluid Into a Dry Poro-Elastic Body

1981 ◽  
Vol 48 (2) ◽  
pp. 259-264
Author(s):  
K. Yamagami ◽  
M. Kurashige
Keyword(s):  
Elastic Body ◽  
Moving Boundary ◽  
The Body ◽  
Moving Boundary Problem ◽  
Whole Body ◽  
Mechanical Behaviors ◽  
Skeleton Model ◽  
Infinite Extent ◽  
Infiltration Front ◽  
Rigid Skeleton

The infiltration of a fluid into a dry poro-elastic body, of infinite extent, from its cylindrical or spherical cavity and the resulting mechanical behaviors are investigated. Since the problem is a moving boundary problem, and therefore, an essentially nonlinear one, the finite-difference scheme with the aid of the boundary fixing method is applied to obtain the solution. The results thus obtained for sandstone are compared with those for a porous rigid body as well as with those in a situation where a fluid pervades the whole body from the outset. These comparisons show that the extent of the infiltration front into the body is adequately predicted by the rigid skeleton model and that the actual stress distribution is remarkably different from that which exists if fluid pervades the whole body from the outset.

scholarly journals Decisions in motion: passive body acceleration modulates hand choice

2017 ◽  
Vol 117 (6) ◽  
pp. 2250-2261 ◽  
Author(s):  
Romy S. Bakker ◽  
Roel H. A. Weijer ◽  
Robert J. van Beers ◽  
Luc P. J. Selen ◽  
W. Pieter Medendorp
Keyword(s):  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Fundamental Aspect ◽  
Dominant Hand ◽  
Target Onset ◽  
Bottom Up ◽  
Right Hand ◽  
The Brain ◽  
Instantaneous Acceleration

In everyday life, we frequently have to decide which hand to use for a certain action. It has been suggested that for this decision the brain calculates expected costs based on action values, such as expected biomechanical costs, expected success rate, handedness, and skillfulness. Although these conclusions were based on experiments in stationary subjects, we often act while the body is in motion. We investigated how hand choice is affected by passive body motion, which directly affects the biomechanical costs of the arm movement due to its inertia. With the use of a linear motion platform, 12 right-handed subjects were sinusoidally translated (0.625 and 0.5 Hz). At 8 possible motion phases, they had to reach, using either their left or right hand, to a target presented at 1 of 11 possible locations. We predicted hand choice by calculating the expected biomechanical costs under different assumptions about the future acceleration involved in these computations, being the forthcoming acceleration during the reach, the instantaneous acceleration at target onset, or zero acceleration as if the body were stationary. Although hand choice was generally biased to use of the dominant hand, it also modulated sinusoidally with the motion, with the amplitude of the bias depending on the motion’s peak acceleration. The phase of hand choice modulation was consistent with the cost model that took the instantaneous acceleration signal at target onset. This suggests that the brain relies on the bottom-up acceleration signals, and not on predictions about future accelerations, when deciding on hand choice during passive whole body motion. NEW & NOTEWORTHY Decisions of hand choice are a fundamental aspect of human behavior. Whereas these decisions are typically studied in stationary subjects, this study examines hand choice while subjects are in motion. We show that accelerations of the body, which differentially modulate the biomechanical costs of left and right hand movements, are also taken into account when deciding which hand to use for a reach, possibly based on bottom-up processing of the otolith signal.

scholarly journals Interaction Preference Differences between Elderly and Younger Exergame Users

2021 ◽  
Vol 18 (23) ◽  
pp. 12583
Author(s):  
Ying Wang ◽  
Yuanyuan Huang ◽  
Junjie Xu ◽  
Defu Bao
Keyword(s):  
Motion Capture ◽  
Interaction Design ◽  
The Body ◽  
Body Motion ◽  
Whole Body ◽  
Heuristic Evaluation ◽  
Four Dimensions ◽  
Body Interaction ◽  
Interactive Games ◽  
Elderly Users

Existing motion capture technology can efficiently track whole-body motion and be applied to many areas of the body. This whole-body interaction design has gained the attention of many researchers. However, few scholars have studied its suitability for elderly users. We were interested in exercise-based whole-body interactive games, which can provide mental and physical exercise for elderly users. We used heuristic evaluation to measure participants’ actions during exergame tasks and analyzed preference differences between elderly and younger users through the distribution of actions in four dimensions. We found that age affected the actions performed by users in exergame tasks. We discuss the mental model of elderly users during the process of performing these tasks and put forward some suggestions for interactive actions. This model and these suggestions theoretically have guiding significance for the research and application of exergame design for elderly users and may help designers develop more effective exergames or other whole-body interaction interfaces suitable for elderly users.

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