1. A method of detecting a posture of at least one predetermined part of an object comprising the steps of: a) extracting a first object shape from a first image taken by a first image sensor; b) computing a characteristic dimension value of said predetermined part within a predetermined region of said first object shape; c) constructing a mask based on said characteristic dimension value; d) extracting a profile of said predetermined part from said first object shape by applying said mask on said first object shape; and e) identifying at least one predefined feature point in said profile of said predetermined part; thereby detecting said posture of said predetermined part.