i with a specified radius r around a first output location o i such that the first output location o i is the center of the circle c i the outer limit ol i of the first annular ring a i may have a radius equal to the radius r of the circle c i plus a half width u03b4r of the first annular ring a i and the inner limit il i of the first annular ring a i may have a radius equal to the radius r of the circle c i minus a half width u03b4r of the first annular ring a i in one implementation the half width u03b4r may be determined based on the size of the seismic survey area 200 in another implementation the radius r may be determined based on the total number of receivers r i in the seismic survey area 200 the annular ring a i may be defined as an area between the outer limit ol i and the inner limit il i around the output location o i although in this implementation the annular rings a i have been described as being circles it should be noted that in some implementations the annular rings a i may be ellipses or other similar shapes at step 120 the annular ring a i may be divided into two or more equal sized segments seg i as illustrated in fig4 fig4 illustrates a schematic diagram describing an arrangement of.