Development of a Calibration Method of Hidden Background Observer Cameras for Diminished Reality Using Radio Direction Finding

Hidden background cameras used to realize Di-minished Reality (DR), which allows the observer to see through obstacles, are installed behind the obstacles. In order to realize DR, it is necessary to measure the positions of these cameras with respect to the observer's position, but this is difficult because the cameras cannot be seen directly from the observer's position. In this study, two calibration methods, the intersection method and the P4P method, which use the directions of radio waves from radio sources mounted on each camera to measure the positions of the hidden background cameras, are proposed. The intersection method measures the direction from several different points to the hidden background cameras and estimate the 3D position of the hidden background camera as the intersection of the measured directions. The P4P method measures the relative pose between multiple hidden background cameras in advance and uses it as a constraint to estimate the 3D poses of the hidden background cameras. The results showed that the P4P method was more accurate than the intersection method, and able to calibrate the camera with a position error of less than 100 mm.