Comparison of the observer, single-frame video and computer vision hand activity levels

Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HAL(O)), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HAL(F)), or (3) from automated computer vision (HAL(C)). This study analysed videos collected from three prospective cohort studies to ascertain HAL(O), HAL(F), and HAL(C) for 419 industrial videos. Although the differences for the three methods were relatively small on average (<1), they were statistically significant (p < .001). A difference between the HAL(C) and HAL(F) ratings within +/- 1 point on the HAL scale was the most consistent, where more than two thirds (68%) of all the cases were within that range and had a linear regression through the mean coefficient of 1.03 (R-2 = 0.89). The results suggest that the computer vision methodology yields comparable results as single-frame video analysis. Practitioner summary: The ACGIH Hand Activity Level (HAL) was obtained for 419 industrial tasks using three methods: observation, calculated using single-frame video analysis and computer vision. The computer vision methodology produced results that were comparable to single-frame video analysis.