Fig. 1. (a) MMS for acquiring road information and (b) work diagram at night

Fig. 2. Laser point cloud display (effect of intensity rendering)

Fig. 3. Flow chart of automatic position and extraction method of manhole covers

Fig. 4. Ground points extraction. (a) Segmentation effect of scanning line; (b) local enlarged view of the scanning line; (c) matrix of laser points

Fig. 5. Experimental data profile (clockwise rotation of 90°)

Fig. 6. Automatic extraction of manhole covers based on MMS. (a) Raw laser point cloud (intensity rendering); (b) ground points (intensity rendering); (c) intensity characteristics image; (d) extraction result of manhole covers

Fig. 7. Manhole cover damage example effect pictures. (a) Original picture; (b) effect picture by enlarging ten times

Fig. 8. Manhole cover ownership information acquisition. (a) Point cloud and image corresponding effect picture; (b) attribute information table of manhole cover