1. A method of decoding hierarchically orthogonal structured light, the method obtaining a 3-D image by encoding the structured light including hierarchically orthogonal address information, radiating the encoded light to a target object, and decoding relevant address from a camera image obtained by capturing the target object to which the encoded light is radiated, the method comprising: a step of detecting boundary lines encoded at an identical position between layers; and a boundary line inheritance step of converting the boundary lines, detected in the step of detecting boundary lines encoded at an identical position between layers, into identical boundary lines.