1. A method for estimating a dimension of a joint of a user in a scene, comprising: receiving, by a computing device comprising a processor and memory, a depth image, the depth image being indicative of the user in the scene; determining, by the computing device, a plurality of proposed dimensions for the joint of the user in the depth image; determining, by the computing device, the dimension of the joint based on the plurality of proposed dimensions; updating, by the computing device, a computer-maintained model that corresponds to the user to have the dimension of the joint, wherein the dimension of the joint comprises a length and a width; and generating, by the computing device, one or more motions or movements by mapping the updated computer-maintained model.