This tool is used to generate a flow pointer grid (i.e. flow direction) using the D-infinity (Tarboton, 1997) algorithm. Dinf is a multiple-flow-direction (MFD) method because the flow entering each grid cell is routed one or two downslope neighbours, i.e. flow divergence is permitted. The user must specify the name of a digital elevation model (DEM) that has been hydrologically corrected to remove all spurious depressions and flat areas. DEM pre-processing is usually archived using the Fill Depressions tool. Flow directions are specified in the output flow-pointer grid as azimuth degrees measured from north, i.e. any value between 0 and 360 degrees is possible. A pointer value of -1 is used to designate a grid cell with no flow-pointer. This occurs when a grid cell has no downslope neighbour, i.e. a pit cell or topographic depression. Like aspect grids, Dinf flow-pointer grids are best visualized using the circular_bw palette.
Grid cells possessing the NoData value in the input DEM are assigned the NoData value in the output image. The output raster is of the float data type and continuous data scale.
The following is an example of a Python script that uses this tool:
wd = pluginHost.getWorkingDirectory()
demFile = wd + "DEM.dep"
outputFile = wd + "pointer.dep"
args = [demFile, outputFile]
pluginHost.runPlugin("FlowPointerDinf", args, False)
This is a Groovy script also using this tool:
def wd = pluginHost.getWorkingDirectory()
def demFile = wd + "DEM.dep"
def outputFile = wd + "pointer.dep"
String[] args = [demFile, outputFile]
pluginHost.runPlugin("FlowPointerDinf", args, false)