Operates on any grid and outputs an indicator (1, 0) grid identifing cells with input values >= the threshold value. The standard use is to use an accumulated source area grid to as the input grid to generate a stream raster grid as the output. If you use the optional input mask grid, it limits the domain being evaluated to cells with mask values >= 0. When you use a D-infinity contributing area grid (*sca) as the mask grid, it functions as an edge contamination mask. The threshold logic is:
src = ((ssa >= thresh) & (mask >= s0)) ? 1:0
This parameter is compared to the value in the Accumulated Stream Source grid (*ssa) to determine if the cell should be considered a stream cell. Streams are identified as grid cells for which ssa value is >= this threshold.
Default: 100
Optional.
This optional input is a grid that is used to mask the domain of interest and output is only provided where this grid is >= 0. A common use of this input is to use a D-Infinity contributing area grid as the mask so that the delineated stream network is constrained to areas where D-infinity contributing area is available, replicating the functionality of an edge contamination mask.
processing.runalg('taudem:streamdefinitionbythreshold', -ssa, -thresh, -mask, -src)