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

The purpose of this study was to compare human static pose estimation data measured with a single-view imagebased system and a multi-camera marker-based system. Thirty participants (20 male/10 female, mean & PLUSMN; standard deviation 29.1 & PLUSMN; 10.0 years old, 1.75 & PLUSMN; 0.10 m tall, 79.1 & PLUSMN; 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 degrees, and standard deviations of the differences between systems ranged from 2.4 to 4.7 degrees. 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.