Detection of the Bolt Loosening Angle through Semantic Key Point Extraction Detection by Using an Hourglass Network

Figure 9

Recognition accuracy and error observed under different shooting distances. (a) Loosening angle with a distance of 20 cm. (b) Loosening angle with a distance of 30 cm. (c) Loosening angle with a distance of 40 cm. (d) Loosening angle with a distance of 50 cm.

(a)

(b)

(c)

(d)