1. A method comprising: determining a first set of depth gradient information based on a first depth map; determining a first threshold parameter corresponding to a first depth gradient value; determining a second set of depth gradient information based on a second depth map; determining a second threshold parameter corresponding to a second depth gradient value; identifying a hand based on the first set of depth gradient information and the first threshold parameter; classifying a surface based on the second set of depth gradient information and the second threshold parameter; determining motion information for the hand; tracking one or more hand gestures based on the motion information; and generating an outline of the hand and the surface in one or more images of a scene containing the hand and the surface.