Characterization of liquid lens monocular camera system for depth estimation.

Abstract

In this paper, the characteristic of a liquid lens monocular camera system to perform depth estimation on a static or moving object is presented. The lens of the monocular camera is based on electrowetting liquid lens. The use of liquid lens avoids the problem of lens breathing or different mean image brightness in the acquire images. A function of the relationship between the lens' voltage, lens' temperature and object distance is described. The resulting function is used in the proposed new methodology for object depth estimation based on depth from focus technique and hillclimbing search. Indoor experimental results for object distance range of 1 m to 8 m with depth resolution of 1 m and 1.5 m, shows root-mean-square error (RMSE) for depth estimation of static object was 21%. Depth estimation of moving object shows standard deviation of the steady-state error of 0.78 m and the RMSE was 1.2 m. The estimated speed of the moving object was 0.47 m/s. Based on the results, the method accurately estimated depth for static object distance of 1 m to 5 m and for moving object was 1 m to 4 m.