Methods and systems are disclosed for determining information about a position of an object within a distribution of materials having different complex conductivities. The method includes: (i) causing current to flow in the distribution； (ii) measuring an electrical signal at each of multiple locations in the distribution of materials in response to the current flow； (iii) providing spatial information about the distribution of materials with respect to a first reference frame, the spatial information indicative of regions of different complex conductivity in the distribution of materials； and (iv) determining the position of the object with respect to the spatial information about the distribution of materials based on measured electrical signals and the spatial information. In certain embodiments, the object is a catheter inserted into a patients heart cavity for cardiac mapping.
