Fig. 1. Schematic of experiment system

Fig. 2. Images of weld before and during welding. (a) Before welding; (b) during welding

Fig. 3. Flow chart of weld center area extraction. (a) Median filtering; (b) centerline extraction of laser stripe；(c) extraction of weld feature points; (d) identification of weld center area

Fig. 4. Weld images and corresponding filtering response maps under noise of different intensities. (a)(b) Weld image interfered by slight noise and corresponding filtering response map; (c)(d) weld image interfered by strong noise and corresponding filtering response map

Fig. 5. Experimental scheme of weld path identification. (a) Welding direction and actual weld path; (b) actual image of butted weld

Fig. 6. Butted weld path identification results. (a)(c) KCF algorithm; (d)(f) proposed algorithm

Fig. 7. Lapped weld path identification results

Fig. 8. Quantitative comparison for butted weld path identification. (a) Comparison of identified weld paths；(b) comparison of identification errors

Fig. 9. Quantitative comparison for lapped weld path identification. (a) Comparison of identified weld paths；(b) comparison of identification errors