1. A method for determining extremities of a user, the method comprising: receiving a depth image; generating a grid of voxels based on the depth image; removing a background included in the grid of voxels to isolate one or more voxels associated with a human target; and determining a location or position of one or more extremities of the isolated human target by performing acts comprising: determining a candidate for the one or more extremities; generating a candidate cylinder based on the grid of voxels; calculating a score for the candidate based on the candidate cylinder; determining whether the score of the candidate exceeds an extremity threshold score; and assigning a value of a voxel in the grid associated with the candidate to the location or position of the one or more extremities when the score exceeds the extremity threshold score.