1. A computer-readable medium including instructions that when executed by an electronic device perform the steps of: receiving a first data set corresponding to a first detection signal transmitted over a first spatial region; receiving a second data set corresponding to a second detection signal transmitted over a second spatial region, the second region having a first sub-region in common with the first region; based on the first data set, assigning a first occupancy value to a first cell in an evidence grid, the first cell representing the first sub-region, the first occupancy value characterizing whether an object has been detected by the first detection signal as being present in the first sub-region; calculating, based on the first and second data sets, the probability that the first occupancy value accurately characterizes the presence of the object in the first sub-region; and displaying a representation of the first sub-region based on the probability calculation.