Fig. 1. Original image

Fig. 2. ow chart of segmentation recognition area

Fig. 3. ROI of arrow marking

Fig. 4. Results of Harris corner detection

Fig. 5. Principle of FAST-9 algorithm

Fig. 6. Detection results of original FAST-9 algorithm

Fig. 7. Precision detection process and results with improved FAST-9 algorithm. (a) Process of precision detection; (b) results of precision detection

Fig. 8. Arrow marking recognition areas. (a) Straight or left; (b) straight; (c) right

Fig. 9. Partial positive and negative sample images. (a) Positive samples; (b) negative samples

Fig. 10. Probability distributions of the first three steps moments of positive and negative samples. (a) First order; (b) second order; (c) third order

Fig. 11. Feature vector distribution

Fig. 12. Illustrative diagram of SVM multi classification method