Evaluating the Agreement of Markerless Motion Capture for Joint Angle Estimation in a Constrained Hallway Setting...

Gait analysis is a valuable approach for understanding human movement, but the space and setup requirements of traditional marker-based systems can limit their use outside specialized laboratories. Markerless motion capture may provide a more flexible option, though its agreement in constrained environments compared with traditional spaces is not well established. This study compared a 10-camera markerless system deployed in a hallway with a traditional 8-camera laboratory setup. Twenty-five healthy adults (15 females, 10 males; age 34 [16] y) completed quiet standing, 60 seconds of self-selected walking, and 5-repetition sit-to-stand tasks at both sites on the same day. Three-dimensional pose estimates were processed to calculate alignment during standing, lower-limb joint kinematics during walking, and trunk flexion during sit-to-stand. Agreement within and between sites was assessed using Pearson correlations, root mean square error, Bland Altman limits of agreement, and intraclass correlation coefficients. Standing and walking outcomes showed excellent agreement (intraclass correlation coefficients ≥ .97; root mean square error < 2.3°; mean differences < 1.1°). Sit-to-stand was more variable (limits of agreement 12°-20°) but remained highly reliable (intraclass correlation coefficients > .96). These findings indicate that a constrained markerless setup can yield kinematic data comparable to a laboratory arrangement, suggesting potential for broader use of markerless approaches in diverse environments.