Overlay options are applied to all currently open plan windows.
Off: Turn the currently selected overlay option
Nodes: Overlays on the data the exact positions of the nodes in the grid used for the calculations
Grid: Overlays on the data the exact position the grid lines for the grid used for the calculations. The intersection of horizontal and vertical grid lines are the same as the node points displayed in the node option
Network: This option displays the drainage paths for the domain. This display is analogous to plotting a river network on a contour map except that the network displayed is the drainage direction for all points on the hillslope. The drainage directions point are calculated by the D8 method which means that they point in the node direction closest to the steepest down slope direction.