A focusing-by-vergence system controlled by retinal motion disparity

We describe a focusing-by-vergence system combining a flow based vergence process with an off-line pre-calibration of the focusing odometry. The vergence process is controlled by the retinal optical flow disparity and the target depth velocity is directly obtained from this disparity. The relationship between the target depth (focused target distance) and the focusing odometry of the motorized lens is obtained by an off-line focusing calibration, using a bivariate polynomial to model the relationship between these parameters. The focusing system is velocity controlled and the focusing velocity is dependent on the target focusing depth velocity and the focal distance velocity. The influence of the focal distance velocity that arise due to the focusing process itself is compensated by the adjustment of the zoom parameter based on a constant magnification approach, or through the modeling of the focal distance as a function of the zoom and focus lens settings