A computer-implemented method of supporting one or more robots within a ground region , the method comprising: accessing a map in which the ground region is tessellated into cells covering respective areas of the ground region , of which some cells are classified as feasible to indicate a respective area is feasible for landing, and some cells are classified as infeasible to indicate the respective area is infeasible for landing; searching the map for clusters of adjoining cells that are classified as feasible, covering clusters of adjoining areas that define sub-regions within the ground region that are feasible for landing; ranking the sub-regions according to a cost metric; selecting one of the sub-regions according to the ranking, the one of the sub-regions thereby a selected sub-region; and outputting a geographic position of the selected sub-region for use in guidance, navigation or control, or any combination thereof, of the one or more robots to land at the selected sub-region within the ground region ; and wherein: the map is expressed as a matrix of first values and second values arranged in the cells to cover the respective areas of the ground region , the first values representing those of the cells classified as feasible, and the second values representing those of the cells classified as infeasible, and searching the map includes searching the matrix for the clusters expressed as sub-matrices with all first values. accessing a map in which the ground region is tessellated into cells covering respective areas of the ground region , of which some cells are classified as feasible to indicate a respective area is feasible for landing, and some cells are classified as infeasible to indicate the respective area is infeasible for landing; searching the map for clusters of adjoining cells that are classified as feasible, covering clusters of adjoining areas that define sub-regions within the ground region that are feasible for landing; ranking the sub-regions according to a cost metric; selecting one of the sub-regions according to the ranking, the one of the sub-regions thereby a selected sub-region; and outputting a geographic position of the selected sub-region for use in guidance, navigation or control, or any combination thereof, of the one or more robots to land at the selected sub-region within the ground region ; and wherein: the map is expressed as a matrix of first values and second values arranged in the cells to cover the respective areas of the ground region , the first values representing those of the cells classified as feasible, and the second values representing those of the cells classified as infeasible, and searching the map includes searching the matrix for the clusters expressed as sub-matrices with all first values. the map is expressed as a matrix of first values and second values arranged in the cells to cover the respective areas of the ground region , the first values representing those of the cells classified as feasible, and the second values representing those of the cells classified as infeasible, and searching the map includes searching the matrix for the clusters expressed as sub-matrices with all first values. <EOS>