Statistical analysis of focal-length calibration using vanishing points

Camera focal-length calibration is analyzed by applying a statistical error model of edge fitting in digital images. The reliability of the focal length is computed from the reliability of the vanishing points, and the reliability of the vanishing points is computed from the reliability of the edges to which lines are fitted. A planar grid pattern is placed in the scene for this purpose, and the 3-D configuration that maximizes the reliability is theoretically derived. Multiple data are then fused by optimally weighted averaging. A real image example is given