As shown in Fig. 4, and represent the center of the initial template and the object’s bounding box in the ’th frame, respectively. and represent credible keypoints of the initial template and that in the ’th frame. and represent the angle between the and keypoints of the initial template and that in the ’th frame. and , respectively, represent the Euclidean distance between the keypoints in the initial template and that in the ’th frame. With the following equations, the relative changing rate of position, scale and rotation angle can be calculated: Display Formula
(7)where median represents the function of calculating median. Set the four vertices’ coordinates of initial tracking box as , its relative offset to the center of initial tracking box is , , in the ’th frame, the vertices’ coordinates of tracking box can be obtained by the following equations: Display Formula
(11)where and , respectively, represent the -coordinate and -coordinate after rotation. are the four vertices’ coordinates of tracking box in the ’th frame. The tracking box of each frame can be obtained through the calculation above.