Systems, apparatuses, devices and methods for body pose tracking are provided that are simple, inexpensive, flexible, accurate and robust. One body pose tracking system includes a mobile device, such as a smartphone, and active or passive marker bands. Images and depth information captured by the smartphone may be analyzed using an Inverse Kinematic (IK) model, and, in certain cases, the IK model solution may be augmented by machine learning. Other body pose tracking systems include an augmented-reality/virtual-reality (AR/VR) head-mounted-display (HMD) and/or AR/VR glasses rather than a smartphone. An AR/VR HMD device may include a depth sensor and multiple environment-facing cameras.