The effect of camera viewing angle on posture assessment repeatability and cumulative spinal loading.

Area of Science:

• Ergonomics and Occupational Biomechanics
• Human Factors Engineering
• Workplace Safety Analysis

Background:

• Video-based workplace task analysis is often constrained by equipment and production line layouts, hindering comprehensive motion capture in a single plane.
• Accurate assessment of 3D working postures and cumulative loading is crucial for preventing musculoskeletal disorders.

Purpose of the Study:

• To determine the effect of camera placement on the accuracy of 3D posture assessment.
• To evaluate the influence of camera angles on the reliability and repeatability of calculated cumulative loading variables.

Main Methods:

• Four video cameras were positioned at varying angles (0, 45, 60, 90 degrees) to capture simultaneous views of four distinct lifting tasks.
• Eleven participants analyzed 16 lifting trials using 3DMatch software, with four repeating the protocol for intra-observer reliability.
• Intraclass correlation coefficients (ICC) were used to assess between-day reliability of calculated loading variables.

Main Results:

• Posture matching agreement was higher for body segments with minimal motion.
• A significant task effect was observed (p < 0.05), but no significant participant main effect.
• Excellent reliability (ICC > 0.75) was found for compression, reaction anterior shear, and extension moment.
• Fair to good reliability (0.4 < ICC < 0.75) was observed for joint anterior and posterior shear.

Conclusions:

• The impact of camera viewing angle on assessing working postural exposure is minimal.
• Multi-camera setups provide reliable and repeatable measures for key biomechanical loading variables in workplace assessments.
• Findings support the use of video-based analysis for ergonomic evaluations, even with varied equipment and line arrangements.