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calc_cumulative_flow_map [2026/07/08 17:19] chrystian [Inputs] Fix input port name |
calc_cumulative_flow_map [2026/08/28 03:09] (current) hermann Sync from local documentation review |
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| ===== Description ===== | ===== 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. | + | Calculates a cumulative flow map from a flow direction map, an optional flow weight map, and an optional flow partition map. Each cell of the resulting map holds the total flow it receives, directly or indirectly, from its neighbors. |
| ===== Inputs ===== | ===== Inputs ===== | ||
| ^ Name ^ Type ^ Description ^ | ^ Name ^ Type ^ Description ^ | ||
| - | | Flow Directions | [[Map Type]] | This map defines the flow directions between cells. | | + | | Flow Directions | [[Map Type]] | Map of possible flow directions between cells. Can hold either a single direction or multiple directions per cell. | |
| ===== Optional Inputs ===== | ===== Optional Inputs ===== | ||
| ^ Name ^ Type ^ Description ^ Default Value ^ | ^ 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 | | + | | Weight | [[Map Type]] | Weight of the flow, that is, how much a cell's flow contributes to the flow of the cell it flows into. When not provided, every cell is treated as having a weight of 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 | | + | | Flow Partition | [[Map Type]] | For a multidirectional flow, indicates how much of a cell's flow goes to each neighbor it flows into. Must have at least 8 layers, one for each neighbor direction: layers 5, 6, and 7 for the neighbors above; layers 4 and 0 for the neighbors to the left and right; and layers 3, 2, and 1 for the neighbors below. When not provided, flow is divided evenly among the cells it flows into. | None | |
| - | | Cell Type | [[Cell Type Type]] | Defines the output map cell type. | Signed 32 Bit Integer | | + | | Cell Type | [[Cell Type Type]] | Cell type of the output map. | Signed 32 Bit Integer | |
| - | | Null Accumulation | [[Integer Value Type]] | Defines the output map null value. | -2147483648 | | + | | Null Value | [[Null Value Type]] | Null value of the output map. Cannot be zero. | Provided automatically | |
| - | | 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 | | + | | Accumulation Is Sparse | [[Boolean Value Type]] | If true, forces the accumulated flow map to be stored as a sparse raster, which stores only non-null cells, trading faster access for lower memory use. This is an advanced port. | No | |
| ===== Outputs ===== | ===== Outputs ===== | ||
| ^ Name ^ Type ^ Description ^ | ^ 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. | | + | | Flow Accumulation | [[Map Type]] | Map of accumulated flow, where each cell holds all the flow it receives directly and indirectly from its neighbors. | |
| ===== Group ===== | ===== Group ===== | ||
| Line 30: | Line 30: | ||
| ===== Notes ===== | ===== 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 used to build Flow Directions must be the same one used by [[Calc Flow Direction Map]] to produce it; see that functor for more on 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. | + | When a cell points to its neighbor on a given side, the functor reads that neighbor's share of the flow from the Flow Partition layer assigned to that side, according to the following layout: |
| - | 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 | | ||
| - | | Layer 5 | Layer 6 | Layer 7 | | + | For example, a cell pointing to its left neighbor reads layer 4 at the same position. If Flow Partition is not provided, the flow is evenly divided among the possible branches. |
| - | | 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. | + | Flow Weight defines how much a cell contributes to the overall accumulated flow. If it is not provided, the functor assumes a weight of 1 for every cell. |
| - | If a partition map is not provided, the flow is evenly divided. | + | Raises an error if Null Value is zero. |
| - | + | ||
| - | 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 ===== | ===== Internal Name ===== | ||