The effect of viewing angle on wrist posture estimation from photographic images using novice raters

Lau, Michael H.; Armstrong, Thomas J.

doi:10.1016/j.apergo.2010.08.008

Cited by 25 publications

(19 citation statements)

References 28 publications

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“…Observation of worker posture in person or by photographic/video analysis is common practice, and analysis of this method has received much attention (Paul and Douwes 1993;Juul-Kristensen et al 2001;Lowe 2004;Lau and Armstrong 2011). During a validation experiment, the photographic method employed here had a mean error of^38 and a variance of 78.Differences in natural hand/handle angle across handle conditions (at most 28 ) were small compared to this error, so it is difficult to make conclusions regarding specific effects.…”

Section: Limitationsmentioning

confidence: 93%

“…Since photographs represent a two-dimensional projection of the actual three-dimensional marker triad positions, 'perspective' or 'parallax' error is introduced by the camera lens when the optical axis is not precisely orthogonal to the local wrist 'RUD' plane (Paul and Douwes 1993;Lau and Armstrong 2011). The camera placement was chosen to minimise this perspective error; however, participant posture during push exertions was not constrained.…”

Section: Camera-based Calculation Validation Protocolmentioning

confidence: 99%

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The natural angle between the hand and handle and the effect of handle orientation on wrist radial/ulnar deviation during maximal push exertions

et al. 2013

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Section: Limitationsmentioning

confidence: 93%

Section: Camera-based Calculation Validation Protocolmentioning

confidence: 99%

The natural angle between the hand and handle and the effect of handle orientation on wrist radial/ulnar deviation during maximal push exertions

et al. 2013

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“…When the camera view is not perpendicular to this plane of motion, perspective error may result. However, studies have shown that accurate posture classification can be attained in these situations [Sutherland et al 2007] and that estimation error due to parallax is often less than would be predicted by the spatial relationship between the camera and the joint observed [Lau and Armstrong 2011]. Nonetheless, when possible, the camera should be oriented perpendicularly to the plane of motion to obtain an ideal view.…”

Section: Camera Movement Stability and Framingmentioning

confidence: 99%

“…An example would be the use of relative length of the hand and fingers to classify wrist posture [Lau and Armstrong 2011]. Wrist flexion/extension is not well observed from a dorsal (back side) view of the hand (Figure 3).…”

Section: Visual Reference Of Posture Angles Improves Performancementioning

confidence: 99%

Observation-based posture assessment: review of current practice and recommendations for improvement.

Lowe¹,

Weir²,

Andrews³

2014

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This document is in the public domain and may be freely copied or reprinted. DisclaimerThis guidance document is not a standard or regulation, and it creates no new legal obligations. It contains recommendations and descriptions of practices that have been shown to enhance observation-based assessment of working posture. The recommendations presented are advisory in nature, informational in content, and intended to assist occupational safety and health practitioners in providing a safe and healthful workplace. Ordering InformationTo receive documents or other information about occupational safety and health topics, contact NIOSH: EXECUTIVE SUMMARYThis report describes an observational approach for assessing postural stress of the trunk and upper limbs that is intended to improve risk analysis for prevention of musculoskeletal disorders. The approach is supported by several recent research studies. These studies have evaluated how much time it takes observers to classify specific trunk and upper limb postures, how frequently observers are likely to make posture classification errors, and the magnitude of these errors. The frequency and magnitude of posture classification errors depend on how many categories (levels) are available from which to classify the specific posture. Recent studies suggest that optimal posture analysis performance is obtained by partitioning trunk flexion range of motion into 4 categories of 30° increments; trunk lateral bend into 3 categories of 15° increments; shoulder flexion into 5 categories of 30°; shoulder abduction into 5 categories of 30°; and elbow flexion into 4 categories of 30°. These categories are suggested because they optimize how rapidly and effectively analysts can visually judge posture. This report also presents more general guidelines for the video recording of posture and for the posture analysis process. Guidelines for video recording address such factors as camera position, field of view, lighting, and duration of recording. Guidelines for posture analysis address enhancements such as the benefits of digital video, computer software, training, and use of visual reference and perspective cues. Information in this report can assist health/safety, ergonomics, and risk management/loss control practitioners who conduct job/ worksite assessments of lifting, pushing, pulling, carrying, and/or manual handling risk factors.

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“…In 2003, the parallax problems could be solved by tracking feature points interior [5]. In 2004, according to feature spots in stereo images, distortion of lens and luminance could be improved [6]. In 2005, in terms of the position of 3D and motion of object, the problems of stereo camera positions and reflections could be adjusted by drawing software [7].…”

Section: Introductionmentioning

confidence: 99%

Instant Preview and Analysis System Implementation of Intelligent Stereo Cameras

Yu¹,

Tsai²,

Tsai³

2018

Preprint

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This study presents an instant preview and analysis system implementation of intelligent stereo cameras (ISCs). A parameter optimization prototype adopted the instant preview and analysis system of the ISCs has been achieved the automatic alignment function, and obtained optimal stereo films with the automatic alignment function by adjusting gap and angle between dual cameras. The instant preview and analysis system of the ISCs with parameter optimization can enhance the quality of stereo films effectively and reduce filmed errors and save retouched cost and time in harsh filmed environment.

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The effect of viewing angle on wrist posture estimation from photographic images using novice raters

Cited by 25 publications

References 28 publications

The natural angle between the hand and handle and the effect of handle orientation on wrist radial/ulnar deviation during maximal push exertions

The natural angle between the hand and handle and the effect of handle orientation on wrist radial/ulnar deviation during maximal push exertions

Observation-based posture assessment: review of current practice and recommendations for improvement.

Instant Preview and Analysis System Implementation of Intelligent Stereo Cameras

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