Accumulates a quantity along the stream network in a catchment
FillAccumulationMap ( handle_fdr , outlet , handle_acc [, "weight", handle_weight] [, "inlets", INLETS ] [, "method", met ] )
integer: handle on the flow direction grid defining the stream network
integer: ID of the outlet pixel, as returned by XY2rec
integer: handle on the raster that will receive the computed values along the stream network. This raster is not created by the function, it must exist before and can be created with functions such as CreateFloatRaster
or CreateConstantRaster
By default, the function accumulates the indicator function along the network i.e. each pixel has a weight equal to 1. If you want to accumulate some local quantity (rainfall, etc.) use the key "weight" followed by the handle of the weight raster.
By default, the function computes the accumulation map in the whole catchment upstream outlet pixel. If you want to exclude some subcatchments use the key "inlets" followed by a vector of inlet IDs. The recursive accumulation will not go further upstream whenever one of these inlets is met.
By default, the function simply sums the indicator or weight raster along the network. If you want to compute the mean instead of the sum (for example to compute the mean rainfall upstream each pixel) then use key "method" in conjuction with value "mean" (the conjuction "method","sum" gives the default behavior).
Accumulates a quantity along the stream network in a catchmnent and writes the values to an existing raster.