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, wherein calculating the probability comprises calculating the probability that the first sub-region represented by the first cell reflects at least one of the plurality of detection signals and the probability that the first sub-region represented by the first cell does not reflect at least one of the plurality of detection signals, wherein each of the first and second spatial regions comprises a respective plurality of volumetric bins, each said bin comprising at least one sub-region, the first sub-region being located in at least one of the bins, each sub-region being represented by a corresponding cell in the evidence grid, wherein calculating the probability further comprises calculating a first probability that each sub-region within a first bin of the first spatial region does not reflect at least one of the plurality of detection signals and a second probability that each sub-region within a first bin of the second spatial region does not reflect at least one of the plurality of detection signals, wherein calculating the probability further comprises calculating a third probability that each sub-region within a second bin of the first spatial region reflects at least one of the plurality of detection signals and a fourth probability that each sub-region within a second bin of the second spatial region does not reflect at least one of the plurality of detection signals, wherein calculating the probability further comprises: calculating a first product of the first probability corresponding to at least one bin of the first spatial region and the third probability corresponding to at least one bin of the first spatial region; calculating a second product of the second probability corresponding to at least one bin of the second spatial region and the fourth probability corresponding to at least one bin of the second spatial region; calculating a third product of the first and second products; and calculating the maximum of the third product.