A computer implemented method for processing measurement data from electrocardiogram, ECG, electrodes on a subject. The method includes obtaining a 3D anatomical model of the torso of the subject, and obtaining a 3D image of the torso of the subject. The three dimensional image is aligned with the three-dimensional model. A position of each electrode in the three-dimensional model is determined from the three dimensional image. The positions of the electrodes in the three dimensional model are used for estimating the distribution, fluctuation and/or movement of electrical activity through heart tissue.