Fig. 1. Stereo vision measurement principle diagram of zoom lens

Fig. 2. Diagram of homography matrix in zoom process

Fig. 3. Diagram of solving binocular external parameters

Fig. 4. (a) Zoom lens binocular cameras; (b) calibration board; (c) calibration board under a large zoom value

Fig. 5. Focal lengths of (a) left camera, (b) right camera and (c)main point of left camera under different zoom values

Fig. 6. Reprojective images. (a) Left and (b) right views in Zoom 45; (c) left and (d) right views in Zoom 55; (e) left and (f) right views in Zoom 65; (g) left and (h) right views in Zoom 80

Fig. 7. (a) Homography matrix error; (b) reprojective point error

Fig. 8. Stereo reconstruction with zoom lens. (a) Reconstruction result with calibration parameters under different zoom values; (b) reconstruction result with the proposed method

Fig. 9. Reconstruction error diagram

Fig. 10. Reconstruction results of standard bench block under different zoom values. (a) Physical map of standard block; (b) reconstruction under zoom value of 50; (c) compared results of (b); (d) reconstruction under zoom value 80; (e) compared results of (d)