Electrical impedance tomography (EIT) utilizes electrodes placed on the surface of a body to determine the complex conductivity distribution within the body. When using a voltage source in EIT, it is necessary to know both the applied voltage and the resulting current with high precision, which cannot be achieved with current systems.

Gaze determines a subjects current line of sight or fixation point. The direction of the eye gaze can express the interests of the subject and is a potential porthole into the current cognitive processes. Existing techniques for eye gaze tracking can be divided into video-based techniques and non-video-based techniques. However, non-video-based techniques are intrusive and interfere with the subject, while video-based techniques have significant shortcomings such as lacking sufficient accuracy and imposing physical constraints on the subject.

This invention is directed to a highly accurate and efficient method and algorithm, namely the Dual-Bootstrap Iterative Closest Point algorithm, for performing image registration generally and retinal image registration in particular. Retinal image registration is challenging. The images are projections of a curved surface taken from a wide range of viewpoints using an un-calibrated camera. The non-vascular surface of the retina is homogeneous in healthy retinas, and exhibits a variety of pathologies in unhealthy retinas.