Adapted Approach for Omnidirectional Egomotion Estimation*

2011 ◽  
Vol 1 (1) ◽  
pp. 1-13 ◽  
Author(s):  
A. Radgui ◽  
C. Demonceaux ◽  
E. Mouaddib ◽  
M. Rziza ◽  
D. Aboutajdine
Keyword(s):  
Optical Flow ◽  
Motion Analysis ◽  
Motion Field ◽  
Camera Motion ◽  
Spherical Representation ◽  
Estimation Process ◽  
Error Measures ◽  
Egomotion Estimation ◽  
Omnidirectional Image ◽  
Omnidirectional Images

Egomotion estimation is based principally on the estimation of the optical flow in the image. Recent research has shown that the use of omnidirectional systems with large fields of view allow overcoming the limitation presented in planar-projection imagery in order to address the problem of motion analysis. For omnidirectional images, the 2D motion is often estimated using methods developed for perspective images. This paper adapts motion field calculated using adapted method which takes into account the distortions existing in the omnidirectional image. This 2D motion field is then used as input to the egomotion estimation process using spherical representation of the motion equation. Experimental results are shown and comparison of error measures are given to confirm that succeeded estimation of camera motion will be obtained when using an adapted method to estimate optical flow.

Adapted Approach for Omnidirectional Egomotion Estimation

2013 ◽  
pp. 1-13
Author(s):  
A. Radgui ◽  
C. Demonceaux ◽  
E. Mouaddib ◽  
M. Rziza ◽  
D. Aboutajdine
Keyword(s):  
Optical Flow ◽  
Experimental Results ◽  
Motion Field ◽  
Camera Motion ◽  
Spherical Representation ◽  
Estimation Process ◽  
Error Measures ◽  
Egomotion Estimation ◽  
Omnidirectional Image ◽  
Omnidirectional Images

Egomotion estimation is based principally on the estimation of the optical flow in the image. Recent research has shown that the use of omnidirectional systems with large fields of view allow overcoming the limitation presented in planar-projection imagery in order to address the problem of motion analysis. For omnidirectional images, the 2D motion is often estimated using methods developed for perspective images. This paper adapts motion field calculated using adapted method which takes into account the distortions existing in the omnidirectional image. This 2D motion field is then used as input to the egomotion estimation process using spherical representation of the motion equation. Experimental results are shown and comparison of error measures are given to confirm that succeeded estimation of camera motion will be obtained when using an adapted method to estimate optical flow.

Images, Imagination, and Movement: Pictorial Representations and Their Development in the Work of James Gibson

Perception ◽  
10.1068/p2976 ◽  
2000 ◽  
Vol 29 (6) ◽  
pp. 635-648 ◽  
Author(s):  
James E Cutting
Keyword(s):  
Vector Field ◽  
Optical Flow ◽  
Spherical Representation ◽  
Pictorial Representations ◽  
The Relationship

For more than 30 years James Gibson studied pictures and he studied motion, particularly the relationship between movement through an environment and its visual consequences. For the latter, he also struggled with how best to present his ideas to students and fellow researchers, and employed various representations and formats. This article explores the relationships between the concepts of the fidelity of pictures (an idea he first promoted and later eschewed) and evocativeness as applied to his images. Gibson ended his struggle with an image of a bird flying over a plane surrounded by a spherical representation of a vector field, an image high in evocativeness but less than completely faithful to optical flow.

scholarly journals The Relationship Between the Contact Force at the Ankle Hook and the Hamstring Muscle Force During the Nordic Hamstring Exercise

2021 ◽  
Vol 12 ◽  
Author(s):  
Mianfang Ruan ◽  
Li Li ◽  
Weiping Zhu ◽  
Tianchen Huang ◽  
Xie Wu
Keyword(s):  
United States ◽  
Motion Analysis ◽  
Contact Force ◽  
Sampling Rate ◽  
Contact Forces ◽  
Camera Motion ◽  
Hamstring Muscle ◽  
Novel Device ◽  
Moment Arms ◽  
Analysis System

A novel device has been developed to assess eccentric hamstring strength during the Nordic hamstring exercise (NHE) by measuring the contact force at the ankle hook (brace). The purpose of this study was to determine the correlation between the force measured at the ankle hook and the hamstring force estimated by a low extremity model. Thirteen male college sprinters were recruited to perform NHE on an instrumented device Nordbord (Vald Performance, Australia). Contact forces were measured at a sampling rate of 50 Hz at the hooks using the uniaxial load cells. 3D kinematics were measured simultaneously at a sampling rate of 200 Hz using a 16-camera motion analysis system (Vicon Motion Analysis, Oxford, United Kingdom) during the NHE. The data were processed with Visual 3D (C-Motion, Germantown, MD, United States) and OpenSim (NCSRR, Stanford, CA, United States) to calculate the knee joint center’s coordinates and hamstring moment arms during NHE. A static low extremity model was built to estimate the hamstring force during NHE. We have observed a significant but not very high correlation (r2 = 0.58) between peak hamstring force and the peak contact force at the ankle hook. The peak contact force measured at the ankle hook can only explain a little more than half of the variations in peak hamstring muscle forces during NHE. Caution must be exercised when assessing the eccentric hamstring strength using the ankle contact force during NHE.

Simulation on Vehicle Platform Based on Decoupled Optical Flow Motion Field Model

2019 ◽  
Vol 39 (4) ◽  
pp. 0415005
Author(s):  
乌萌 Wu Meng ◽  
郝金明 Hao Jinming ◽  
付浩 Fu Hao ◽  
高扬 Gao Yang
Keyword(s):  
Optical Flow ◽  
Field Model ◽  
Motion Field ◽  
Flow Motion ◽  
Vehicle Platform

The relationship of hip rotation range, hip rotator strength and balance in healthy individuals

2020 ◽  
Vol 33 (5) ◽  
pp. 761-767
Author(s):  
Yongwook Kim ◽  
Seungmook Kang
Keyword(s):  
Motion Analysis ◽  
External Rotation ◽  
Dynamic Balance ◽  
Three Dimensional ◽  
Camera Motion ◽  
3D Motion ◽  
3D Motion Analysis ◽  
Balance Ability ◽  
Analysis System ◽  
The Relationship

BACKGROUND: Few studies have explored the relationship between muscle strength, range of motion (ROM), and balance in the horizontal plane of the hip joint using three-dimensional (3D) motion analysis. OBJECTIVE: We investigate the relationships of hip internal rotation (IR) and external rotation (ER) ROM, measured using a 3D motion capture system, with hip internal and external rotator strength and single-leg standing balance. METHODS: The participants were 40 healthy adults. Kinematic data on hip ROM were collected using an eight-camera motion analysis system. Hip rotational strength measurements were obtained using hand-held isometric dynamometry. A Single-leg standing test and a pendular test were conducted to evaluate static and dynamic balance ability using BioRescue. RESULTS: Significant correlations were found between hip strength and each variable measured during hip ROM assessments (p< 0.05). Significant positive correlations were found between the hip IR/ER strength ratio and the IR/ER ROM ratio (r= 0.72, p< 0.01). The subgroup with a normal IR/ER ratio of hip rotator strength and ROM showed significantly better dynamic balance ability than the subgroup with a hip rotator muscle imbalance (p< 0.05). CONCLUSIONS: There is a significant relationship between hip IR/ER strength and IR/ER ROM with a normal hip IR/ER strength and ROM ratio positively affecting dynamic balance ability.

Sign in / Sign up

Export Citation Format

Share Document