ETG_CostAllocationRaster

Cost Allocation - Costs from Raster

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:

Input feature dataset - Sources (Point, Polyline, Polygon)
Output raster name and format
A Cost raster - full name to the 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 feature (Source). The extent of the output is equal to the extent of the input feature class.
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.

Example:

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:

The output Cost Allocation raster will have the spatial reference of the input Cost raster dataset.
The Cost raster can not have cells with negative or zero values - the cost can not be 0 or negative.
Cell locations with NoData in the Cost raster act as barriers.
The input format accepted are file based rasters - ERDAS IMAGINE or Tagged Image File Format (TIFF).
The .NET ToolBox for ArcGIS Desktop accepts also FileGDB Raster inputs.
For file based rasters initially the name of the output raster define the raster format:
- .img extension (for example raster1.img) - ERDAS IMAGINE image.
- .tif extension (for example raster1.tif - image.
- The initial output raster format can be changed by selecting the desired output in the dialog.

Running Programmatically

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Parameters

Expression	Explanation
Function Name	CostAllocationRaster
<InputFeatures>	A String - the full path to the input feature dataset.
<output raster>	A String - the full name of the output raster.
<CostRaster>	A String representing the cost raster dataset.
<IDField>	A String representing the name of the field in the input point feature class to be used as point ID.
<CutOff>	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.

Running the function

ETSPath used in the table below is the full path to ETSRun.exe (E.G. "C:\Program Files\ETSpatial Techniques\ETSurface\ETSRun.exe")

CostRaster

Language	Syntax
Python	subprocess.call([ETSPath, "CostAllocationRaster", "InputFeatures", "output raster", "CostRaster", "IDField", "CutOff"])
.NET using ETSRun.exe	StartInfo.FileName = ETSPath StartInfo.Arguments = "CostAllocationRaster" "InputFeatures" "output raster" "CostRaster" "IDField" "CutOff"
.NET using ETSOutX.dll	CostAllocationRaster(InputFeatures, output raster, CostRaster, IDField, CutOff)
ArcPy	arcpy.CostAllocationRaster("InputFeatures", "output raster", "CostRaster", "IDField", "CutOff")

Notes:

<> - required parameter
{} - optional parameter
See examples for Python , .NET or ArcPy
The argument separator for StartInfo.Arguments is space. If a string might contain a space, you need to double quote it.

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