Calibration Procedure of Camera With Multifocus Zoom Lens for Three-Dimensional Scanning System

Abstract

With zoom lenses, both the magnification of the camera and the distance between the lens and the object plane can be changed. Changes to zoom lens magnification is accompanied by changes in the depth of field and the distance between the lens and the object plane, complicating the calibration of zoom cameras—specifically, that of each focus and zoom control, for which separate configurations are required. To overcome this problem, a procedure for the calibration of a multifocus zoom lens in a three-dimensional (3D) scanning system was developed in the present study. Specifically, a pragmatic, five-step calibration procedure was proposed. In the first two steps, the characteristics of the zoom lens were obtained. In the third and fourth steps, the calibration was normalized. Finally, the effectiveness of the process was assessed using a laboratory-developed prototype. High reconstruction accuracy was achieved.

Keywords

• Active optical scanner
• camera calibration
• zoom lens
• zoom-dependent calibration
• reconstruction accuracy