The accuracy of imaging cardiac sources using electrocardiographic and magnetocardiographic signals is influenced by thoracic inhomogeneities, e.g. the lungs and cardiac blood masses. The effects is investigated of such inhomogeneities on the body-surface potential maps (BSPM) and magnetic-field maps (MFM) inverse solutions for a single moving dipole as the source model and a realistic torso model as the volume conductor, by employing a node-based boundary element method. Using the same number and placement of the body-surface potential and magnetic field leads, a comparison is obtained of the numerical accuracy of body-surface potential and magnetic field leads. The results show that, with no noise added, the body-surface potential solution is less sensitive to the exclusion of the inhomogeneities than the magnetic field solution. The influence of noise on the BSPM and MFM localization is comparable for x (left-right) and y (foot-head) oriented dipoles, and the BSPM localisation is more accurate than the MFM localisation for z (anterior-posterior) oriented dipoles.