Images from a second pattern covering the whole ROI of the scene are acquired for computing the extrinsic parameters of the camera model. This pattern consists of a 13×4 matrix of black rhombuses, where reference points are the centroid of each rhombus. The height of the pattern covers the height of the ROI of the scene but does not cover the whole width. Thus, the pattern is moved horizontally to acquire a set of images in which the pattern covers the whole ROI of the scene. Figure 12 shows an example of the images taken for extrinsic calibration in the roll path of a steel strip production line, where the pattern is located at the center of the ROI of the scene.