Comparison of a single-view image-based system to a multi-camera marker-based system for human static pose estimation

Abstract

The purpose of this study was to compare human static pose estimation data measured with a single-view image-based system and a multi-camera marker-based system. Thirty participants (20 male/10 female, mean ± standard deviation 29.1 ± 10.0 years old, 1.75 ± 0.10 m tall, 79.1 ± 18.0 kg) performed six repetitions each of static holds of arm-raises and squats, in a different orientation for each repetition. These trials were captured simultaneously with a 120-Hz 12-camera marker-based system and a variable-frequency single-view image-based system. Data for each trial were time-synchronized between the two systems using a near-infrared LED-light that was visible to both systems. Discrete measurements of bilateral shoulder angles during arm-raises and bilateral knee angles during squats were compared between the systems using Bland-Altman plots and descriptive statistics. Pearson correlation coefficients were calculated, comparing the participant trial mean values across systems. Finally, a two-way ANOVA was used to examine whether participant orientation in the capture volume significantly affected either system. Biases for discrete measurements ranged in magnitude from 1.3 to 1.9°, and standard deviations of the differences between systems ranged from 2.4 to 4.7°. Pearson correlation coefficients were all above 0.97, and the ANOVA was unable to find a statistically significant orientation effect for either system. Thus, the marker-based and image-based systems produced similar measurements of static shoulder and knee angles. Future work should examine more complex measurements using volumetric scan-based models and also investigate the ability of single-view image-based systems to measure dynamic movements.