Calc Cumulative Flow Map

Description

This functor calculates a cumulative flow map using a flow direction map, an elevation map and a flow partition map. The resulting map indicates the flow received by every cell directly and indirectly.

Inputs

Name	Type	Description
Flow Directions	Map Type	This map defines the flow directions between cells.

Optional Inputs

Name	Type	Description	Default Value
Weight	Map Type	Weights ponder the cell flow, in terms of contribution. If this map is not provided, the functor assumes that weight is always 1.	None
Flow Partition	Map Type	This parameter defines the percentage of the flow transfered among cells. If the functor does not receive this map, it is assumed that the flow is equally divided among the cells pointed by the “Flow Directions” map.	None
Cell Type	Cell Type Type	Defines the output map cell type.	Signed 32 Bit Integer
Null Accumulation	Integer Value Type	Defines the output map null value.	-2147483648
Accumulation Is Sparse	Integer Value Type	If true, the map is loaded as a sparse image. Sparse images have the advantage of storing only the cells containing non-null values, yet have diminished access time.	False

Outputs

Name	Type	Description
Flow Accumulation	Map Type	Map where each cell represents the accumulated flow. The resulting flow comprises the flows received from the neighbors directly and indirectly.

Group

Map Algebra

Notes

The direction map indicates the possible flow direction from every cells. See Calc Flow Direction Map for further information about the flow direction map.

The elevation map must be the same map used to calculate the flow direction map. See Calc Flow Direction Map for further information.

The flow partition map is used to indicate how much flow goes into every possible branch (in case of a multidirectional flow source). This map must have at least 8 layers. Each layer corresponds to one of the cell neighbors as follows:

Layer 5	Layer 6	Layer 7
Layer 4	Layer 0
Layer 3	Layer 2	Layer 1

Example: If the central/anchor cell points toward the left neighbor, the functor searches the partition information on the 4th layer at the same position of the cell.

If a partition map is not provided, the flow is evenly divided.

The weight map defines how much a cell contributes to the overall accumulated flow. If a weight map is not provided, the functor assumes a weight of 1 for all cells.

Internal Name

CalcCumulativeFlowMap