Ellipse fitting of short light stripe for structured light based 3D vision inspection

Structured light based 3D vision has wide applications in inspecting the form and position errors like straightness and coaxiality of cylindrical workpieces. But for these applications, the light stripe on the workpiece's surface is much too short, and contains inadequate data information, even with some noise. Under such circumstances, the ellipse fitting to the scattered data of the light stripe is not efficient enough, and its fitting accuracy is usually poor. To address this problem, a new least-square fitting method based on the constraint of ellipse minor axis (called CEMA method) is proposed in detail in this paper. Simulations are given for the proposed method and for five other popular methods described in the literature. The results show that the proposed method can efficiently improve the accuracy and the robustness of ellipse fitting to the scattered data of short light stripe.