Object Tracking in a 3-Dimensional Environment

The movement of an object is tracked in a 3D environment. In some cases, the object is a hand which may be used for gesture input to an augmented reality system. In a particular implementation, 3D images of the environment may be captured and 2D contours of objects within the environment may be generated. Overlap between regions defined by the 2D contours of objects in the 3D images may be utilized to determine whether an object in a first 3D image is the same as an object in a second 3D image that is captured subsequent to the first 3D image.