A system includes an Interferometric radar that transmits a first detection signal over a first spatial region and a second detection signal over a second spatial region. The second region has a first sub-region in common with the first region. The system further includes a processing device that assigns a first occupancy value to a first cell in an evidence grid. The first cell represents the first sub-region, and the first occupancy value characterizes whether an object has been detected by the first detection signal as being present in the first sub-region. The processing device calculates, based on the first and second detection signals, the probability that the first occupancy value accurately characterizes the presence of the object in the first sub-region, and generates a data representation of the first sub-region based on the probability calculation.