## 2 Materials and Methods  
### Experimental Procedures  
Sixteen participants (8 male and 8 female, aged 22-59 years) were recruited following approval by the University of Guelph Research Ethics Board (REB #22-05-004). Prior to study participation, all participants provided virtual written consent. Four GoPro Hero 11 Black cameras (GoPro, San Mateo, CA, USA) were positioned at varying heights and locations in an attempt to optimize the field of view to include participant upper extremity motion (Figure 1). The capture volume was set to ensure that the participant's upper limbs were visible in all FOVs and the participants were required to stand on a marker which was taped to the ground. As noted in literature, to achieve relevant 2D angles, a camera must be aligned with the plane of motion [31]. Study participants would complete right arm actions with their left arm at their side; therefore, cameras were arranged to provide right-side, frontal, overhead, and oblique views to encompass a variety of common movement planes. Three of the cameras were aligned parallel to the floor while the oblique camera was tilted 30\({}^{\circ}\) towards to the floor, 8\({}^{\circ}\) higher than the right-side and frontal cameras and 8\({}^{\circ}\) below the overhead camera. This positioned the oblique camera at an approximately centralized height. To achieve the highest quality video footage possible, the video was recorded at a resolution of 2704 \(\times\) 1520 (2.7 k) with a framerate of 120 frames per second (fps). Calibration trials for the GoPro camera system were recorded prior to all participant trials using a ChArUco board (OpenCV version 4.7, Palo Alto, CA, USA. [[https://opencv.org/](https://opencv.org/)]([https://opencv.org/](https://opencv.org/)), accessed on 6 February 2024) [37] with a 5 \(\times\)7 grid, 36 mm checkers, 28 mm markers, and a 7 \(\times\) 7 ArUco dictionary. Another calibration trial was recorded prior to individual participant trials to ensure that the calibration had not changed. The 4 GoPro Hero 11 Black cameras (GoPro, San Mateo, CA, USA) simultaneously recorded for approximately 1 min while the ChArUco board was tilted in all directions of the defined recording volume such that multiple cameras were able to view the target at the same time. These calibration trials were used later to determine intrinsic, extrinsic, and distortion parameters for the cameras as described by [38]. These parameters were then used to calibrate the positions of the cameras relative to each other using iterative bundle adjustment as described by [24]. In parallel, a 13-camera (10 Bonita, 2 Vero, 1 Vue) VICON optical motion capture system recording at 120 fps was used to collect ground truth wrist kinematic data. The VUE camera is capable of recording RGB video simultaneously with the remaining 12 (Bonita and Vero) infrared cameras. An Arduino Uno circuit placed in the field of view (FOV) of the GoPro cameras and the VUE camera was used to flash 3 different colored LEDs in rapid succession when triggered by an external remote. These LED flashes were used as a visual trigger to synchronize the video footage between each GoPro and the VICON VUE camera at the beginning of each participant trial. For each participant, nine 7.9 mm spherical retroreflective markers were placed on metacarpophalangeal joints (mcp) 2, 3, and 5; the radial and ulnar styloid processes; the midpoint between the radial and ulnar markers; the lateral and medial humeral epicondyles; and the center of the humeral epicondyle (Figure 2). The marker set was a modified version of the upper/lower arm segment defined for use in Visual3D [39] (Table 1). The joint coordinate system was defined according to the International Society for Biomechanics (ISB) guidelines [40] with a detailed definition as used by [41]. The center wrist marker was added to both the Visual3D markerset and referenced coordinate system to provide an additional point for tracking.