1. A non-transitory computer-readable medium having instructions executable by a processor, the instructions comprising: a plurality of data sets including values computed for each of a plurality of points for a given spatial region of tissue, the values in each of the data sets being calculated to characterize electrical information for each respective point of the plurality of points for a different time interval; a composite map generator programmed to combine the values computed for each of a plurality of points in a first interval, corresponding to a first map, with the values for computed for each of the respective plurality of points in another interval and to normalize the combined values relative to a common scale; and an output generator programmed to generate a composite map for the given spatial region based on the combined values that are normalized.