Fig 5. Homography and coordinate frames.

a. The angled view of the homography rectangle marked in red and corners numbered from the CCTV camera. The green dots mark the points corresponding to a person’s feet in this view. b. The top view of the homography rectangle after transformation and the origin of the top view coordinate system is marked as o_top. The coordinates of the feet points are also transformed using the homography matrix. c. A map of the robot’s environment with free space denoted in gray and obstacles denoted in black with a coordinate frame at origin o_map. The homography rectangle is marked in red and the ground plane coordinate system is shown with the origin o_gnd.