A. Data Storage
A single smartphone recording continuously for a period of 24 hours at a frame rate of 30f/s would equate to approximately 2.5 million database entries. Consequently, the motion cloud’s database (shown in Fig. 5) is designed to be efficient to accommodate large amounts of data. Users are required to register a unique account by providing general profile information and authentication credentials. Once authenticated using the OAuth authorization protocol, the user can create new recordings or access previous recordings. Each recording object is paired with a configuration table entry that stores settings such as frame rate, recording timestamps and a hash value corresponding to the kinematic rig in use. Finally, each recoding contains a set of channels that store vector readings corresponding to rotations (as found in BVH files) and gravitational accelerations.