Fig. 1. Schematic of markers. (a) Diagonal marker; (b) cross marker; (c) coded marker; (d) circular marker

Fig. 2. Speckle image

Fig. 3. (a) Binocular stereoscopic vision measurement system; (b) schematic of marker tracking

Fig. 4. Schematic of improved KLT algorithm

Fig. 5. Removal principle of mismatch marker

Fig. 6. Experimental setup

Fig. 7. Measurement results of markers. (a) Images of original markers; (b) measurement result of traditional SURF algorithm;(c) DOG image of markers; (d) OTSU segmentation image; (e) measurement result of improved SURF algorithm

Fig. 8. Matching diagrams of markers. (a) Matching diagram using unimproved KLT algorithm; (b) matching diagram using improved KLT algorithm; (c) matching diagram when mismatching points are removed

Fig. 9. Experimental results. (a) Matching time; (b) matching accuracy