Fig. 1. Layout of the surface to be measured, a laser and cameras

Fig. 2. Examples of image preprocessing. (a) Experimental surface after irradiating; (b) partial enlarged image after binaryzation; (c) partial enlarged image after de-noising; (d) partial enlarged image after thinning

Fig. 3. Partial enlarged images of different types of connected points. (a) Double angle type; (b) T and angle type; (c) point and angle type; (d) T and point type; (e) cross type; (f) overlapping type

Fig. 4. Partial enlarged images of connected points after filtration. (a) Double angle type; (b) T and angle type; (c) point and angle type; (d) T and point type; (e) cross type; (f) overlapping type

Fig. 5. Partial enlarged images of connected points after second filtration. (a) Double angle type; (b) T and angle type; (c) point and angle type; (d) T and point type; (e) cross type; (f) overlapping type

Fig. 6. Comparison of two feature point extraction algorithms

Fig. 7. Example of minimum distance distribution between feature points

Fig. 8. Example of matching result

Fig. 9. Extraction and matching results of left and right cameras. (a) Pot; (b) grid plate; (c) china cup

Fig. 10. Extraction results of feature points in different references. (a) Ref. [20]; (b) Ref. [14]; (c) Ref. [16]; (d) Ref. [17]

Fig. 11. Objects to be measured. (a) Grid plate plane; (b) white paper plane; (c) stripe paper plane