Fig. 1. Simulation results. (a) Simulation of two-dimensional fiber; (b) grayscale in th actual direction; (c) vector weighted algorithm; (d) proposed algorithm

Fig. 2. Diagram of four angles in three-dimensional space

Fig. 3. Three-dimensional simulated fiber. (a) Diameter of 3 pixel; (b) diameter of 9 pixel; (c) diameter of 15 pixel

Fig. 4. Direction measurement errors corresponding to different windows and fiber diameters. (a) Error of ?; (b) error of θ

Fig. 5. Measurement error comparison between proposed algorithm and vector weighted algorithm

Fig. 6. Relationship between number of fibers and measurement error

Fig. 7. Consuming time comparison between vector weighted algorithm and proposed algorithm

Fig. 8. 100 simulated fibers with different directions, length, and diameters