1. A geospatial modeling system comprising: a geospatial model data storage device; and a processor cooperating with said geospatial model data storage device for determining a void within a geospatial model data set defining a void boundary region, selecting at least one raw fill region from within the geospatial model data set for filling the void, adjusting elevation values of the at least one raw fill region based upon elevation differences between corresponding portions of the void boundary region and the at least one raw fill region, and updating the geospatial model data set based upon the adjusted elevation values of the at least one raw fill region.