Fig. 1. Structure of a high voltage transmission line

Fig. 2. Inspection robot

Fig. 3. Flow chat of barriers identification

Fig. 4. Homomorphic filtering process

Fig. 5. Homomorphic filter function

Fig. 6. Comparison of images before and after image filtering. (a) Before filtering; (b) after filtering

Fig. 7. Kirsch eight direction templates

Fig. 8. LDP coding process

Fig. 9. CLDP coding process

Fig. 10. Comparison of LDP and CLDP algorithms feature extraction

Fig. 11. Histogram extraction of obstacles image CLDP

Fig. 12. Part of the obstacle image sample. (a) Suspension clamp; (b) count weight; (c) insulator chain

Fig. 13. AH-CLDP recognition rate at different fixed values of c

Fig. 14. Recognition rate under different sample sizes. (a) Count weight; (b) suspension clamp; (c) insulator chain