D8 flow routing: each cell drains to its steepest strictly-lower neighbour, or is an outlet (−1). Sea cells (at or below seaLevel in the unfilled heights) are always outlets.
seaLevel
heights
D8 flow routing: each cell drains to its steepest strictly-lower neighbour, or is an outlet (−1). Sea cells (at or below
seaLevelin the unfilledheights) are always outlets.