Ghost3D: detecting body posture and parts using stereo

The paper describes how to detect human posture and upper body parts using overhead narrow-baseline stereo cameras. This information is extracted to understand retail customer behavior while shopping. We propose an approach to detect body posture without using an explicit 3D human model. The proposed method is based on a 3D silhouette, a silhouette-ghost of a person, that is constructed from a 2D silhouette. The 2D silhouette is detected by color and disparity background subtraction. Once the silhouette-ghost is generated, the head and shoulder regions are identified using the human body topological structure which constrains the relative position of each body part. A shape histogram, the distribution of relative positions of points on a 3D silhouette, is introduced to estimate the posture and body parts.