Locates the cells verifying a transition criterion when moving downstream in a channel network.
CELLS = FindNetworkTransition ( handle_ras , handle_fdr , a , b , outlet , niter )
integer: handle on the raster which will be used to define the transition criterion.
integer: handle on the flow direction grid to be used.
floats: the transition criterion will be verified when the expression (a * #Raster# + b) switches from positive to negative when moving downstream.
integer: record number (absolute reference in the raster, as returned by XY2rec
) of the outlet cell.
integer: number of times that the search for transitions can be performed recursively.
output: vector containing the record numbers of the cells verifying the transition criterion.
Locates the cells verifying a transition criterion when moving downstream in a channel network.
if the raster elev
contains elevation data, then the contour line Z=Z0
in the catchment having its outlet at cell outlet
, is given by the set of cells verifying the following transition :
1 * #elev# - Z0
switching from positive to negative when moving downstream, i.e. :
CZ0 = FindNetworkTransition ( elev , fdr , 1 , -Z0 , outlet , 1)