Flag signal identification method and apparatus based on depth image

The invention discloses a flag signal identification method and apparatus based on a depth image. The method comprises the following steps: (10), according to a human body motion depth image, segmenting a human body from a background, gradually refining a human body area, and extracting a human body skeleton line; (20), based on an articulation point space relation human body model, describing a human body arm motion by use of the human body skeleton line; (30), according to an arm different space position and motion locus composed of three components including an upper arm, a forearm and a wrist, defining an arm gesture mode; and (40), through matching between the arm gesture mode and a predefined motion mode in a flag sign database, taking a predefined motion most similar to the arm gesture mode as a flag sign corresponding to the human body motion. The apparatus comprises a human body skeleton feature extraction unit, a human body motion describing unit, an arm gesture mode defining unit and a flag sign identification unit. The method and apparatus provided by the invention is less affected by environment factors and is good in real-time performance and high in identification rate.