1. A system for capturing motion data in natural environments, comprising: a set of sources arranged on an object capable of undergoing motion, in which each source is configured to emit ultrasonic signals; a set of sensors arranged on the object, in which each sensor is configured to detect the ultrasonic signals; a driver module arranged on the object, in which the driver module is configured to generate the ultrasonic signals for the set of sources and timing signals for the set of sensors, and in which the ultrasonic signals are synchronized to the timing signals; means for measuring distances between the set of sources and the set of sensors based on a time of flight of the ultrasonic signals; a set of inertial components arranged on the object; means for determining 3D orientations of the set of inertial components; and means for determining 3D locations of the set of sources and the set of sensors from the distances to capture motion data of the object, in which the 3D locations and the 3D orientations determine a six degree of freedom pose with respect to a world coordinate system, and wherein the six degree of freedom pose is determined using inverse kinematics processes.