3D Target Scale Estimation for Size Preserving in PTZ Video Tracking

In size preserving video tracking, the camera's focal length (zoom) is adjusted automatically to compensate for the changes in the target's image size caused by the relative motion between the camera and the target. The accurate estimation of these changes is paramount to the system performance. Structure from motion (SFM) based on the weak perspective projection model has been applied to real time target scale estimation (B. Tordoff, et al., 2004). In this paper we design target scale estimation algorithms with linear solutions based on more advanced projection models: paraperspective and perspective. The performances of the algorithms using three projection models are examined and compared. Experimental results show that the proposed algorithm based on the paraperspective projection model produces the best performance with respect to accuracy, complexity, and robustness.