1. A method for determining a voltage distribution on a surface of a tissue, comprising: receiving a plurality of voltages collected by a plurality of electrodes adjacent to the surface; introducing one or more regularization terms to an error minimization formulation; and solving, by a processor, the voltage distribution according to said plurality of voltages and according to said regularization terms of the error minimization formulation; wherein a first of said regularization terms comprises a Laplacian smoothness operator and another of said regularization terms comprises a Tikhonov regularization matrix.