Printed checkerboard mounted to a flat surface This checkerboard worked great for us. It is important to mount the checkerboard to a flat surface (e.g., plexiglass sheet) and not to cover it with a reflective surface (e.g., don't laminate it).
Install the TestFlight app from the App Store
Install the OpenCap app by scanning this QR code or by using this link
OpenCap is developed at Stanford University in the Neuromuscular Biomechanics Laboratory under the supervision of Prof. Scott Delp. The project is supported by the Wu Tsai Human Performance Alliance at Stanford University, the Mobilize Center, a Biomedical Technology Resource Center funded by the National Institutes of Health under Grand P41EB027060, and the Restore Center, a Medical Rehabilitation Research Resource Center funded by the National Institutes of Health through Grant P2CHD10191301.