A method, by an augmented reality device, of measuring a depth of an object includes determining, from a dot-pattern and a surface-pattern, a pattern of light to be emitted for measuring the depth of the object, identifying, from within an entire area of a pattern generator, a partial area of a light source unit corresponding to an area for the determined pattern, emitting light through the area for the determined pattern, by activating the identified partial area of the light source unit, receiving light reflected from the object; and measuring the depth of the object based on the emitted light and the received reflected light.