Three-dimensional (3-D) spatial image data may be received that is associated with at least one arm motion of an actor based on free-form movements of at least one hand of the actor, based on natural gesture motions of the at least one hand. A plurality of sequential 3-D spatial representations that each include 3-D spatial map data corresponding to a 3-D posture and position of the hand at sequential instances of time during the free-form movements may be determined, based on the received 3-D spatial image data. An integrated 3-D model may be generated, via a spatial object processor, based on incrementally integrating the 3-D spatial map data included in the determined sequential 3-D spatial representations and comparing a threshold time value with model time values indicating numbers of instances of time spent by the hand occupying a plurality of 3-D spatial regions during the free-form movements.