Cost Allocation - Costs from Raster
Open Table of Contents ToolBox Implementation
Derives the catchment areas of the input features (Sources) using their spatial location and the weights from a weight raster. The function allocates the cells of the output raster to the sources based on minimum cost to reach a source from the cell. The cost is calculated as distance from the cell to the source multiplied by the weight of the cells of the cost raster. The NODATA values in the cost raster are considered prohibitive cost.

Inputs:

  • A point feature class (Sources).
  • A Cost raster
  • Source ID field. The values from this field will be allocated to the cells of the output raster.
  • Cutoff cost - cells with larger than this cost (distance x weight) to reach will not be allocated to any source.

Outputs:

  • An integer raster. Each cell will have as a value the ID of the closest input point (Source).
    • The extent of the output is equal to the extent of the input cost raster.
    • The cell size of the output is equal to the cell size of the input cost raster.

Examples:
Source points

Cost Raster - Slope raster of digital terrain model used in the example.

The scenario might be to allocate emergency response areas to centers in a mountain - the larger the slope - the lower the accessibility.
 
The resulting allocation raster.
The resulting allocation raster over the Hillshade of the terrain. Illustrates that the boundaries of the zones allocated to the Centers are on very steep terrain (slope is big - the cost is high).

Notes:

  • Initially the name of the output raster defines the raster format
    • no extension specified - ESRI binary GRID
    • .img extension (for example raster1.img) - ERDAS IMAGINE image.
    • .tif extension (for example raster1.tif - Tagged Image File Format (TIFF) image.
  • The initial output raster format can be changed by selecting the desired output in the dialog.
  • Currently only file based rasters are supported. Rasters cannot be stored in a GeoDatabase. After you get the desired result, you can export the raster to a GeoDatabase using the standard ArcGIS tools.
  • The input feature class and cost raster must be in the same projected coordinate system.
  • The result raster can be easily converted to a polygon feature class using the standard ArcGIS Raster To Polygon tool
  • The attributes can be transferred to the polygons by joining the Raster Attribute Table to the polygons using GRID_CODE field of the feature class and the Value field of the raster attribute table.

ToolBox implementation

Command line syntax

ETS_GPCostAllocationRaster <Input Points> <Cost Raster>  <Out Raster> <ID Field> {Cut Off Cost}

Parameters

Expression Explanation
<Input Points> A Point layer feature class
<Cost Raster> A Raster dataset or Raster layer
<Out Raster> A String - the full name of the output raster (A raster with the same full name should not exist). The output raster type depends on the extension of the output file(see Notes above)
<ID Field> A String representing the name of the field in the input point feature class to be used as point ID.
{Cut Off Cost} A Double representing the cut off cost - the value of the cells with larger than this cost (distance x weight) to reach will be set to NODATA

Scripting syntax

ETS_GPCostAllocationRaster (Input Points, Cost Raster, Out Raster, ID Field, Cut Off Cost)

See the explanations above:
<> - required parameter
{} - optional parameter

All ESRI products mentioned are trademarks of Environmental Systems Research Institute, Inc.
Copyright: Ianko Tchoukanski