The Optimal Path As Line tool produces an output line feature service that records the least-cost path, or paths, from sources the closest destination defined within the accumulative cost surface or Euclidean distance surface.
If you have destination features, you can convert them to an image service using the Rasterize Features raster function. Use your existing Cost Distance Raster as the Raster input to the rasterization function. This will ensure that the features are properly converted to an image service using the same cell size, extent, and spatial reference.
The NoData values that exist in the Destination Raster are not included as valid values in the function. The value 0 is considered a legitimate value in the destination raster.
Two input image services are needed to run Cost Path As Polyline. How you generate these inputs depends on the type of analysis you want to complete.
- Cost analysis generates a cost path. Run the Cost Back Link and Cost Distance raster functions to generate necessary inputs.
- Euclidean analysis generates straight line paths and paths around barriers. Run the Calculate Distance tool to generate Euclidean Back Direction and Euclidean Distance. Alternatively run the Euclidean Back Direction and Euclidean Distance raster functions.
- Flow analysis generates flow paths. Run the Flow Direction raster function using the D8 option. Use a D8 flow direction raster as input for the Input Cost Backlink Raster. You also need to supply an Input Cost Distance Raster; the Input Cost Distance Raster is not used to determine the path. Whether you use a constant raster or a digital elevation model (DEM), your path will be the same; only an attribute value on your path will vary.
The output feature service has an field called DestID that identifies the destination to which each line leads.
Unlike most other Raster Analysis tools, Cost Path As Polyline will ignore the following environment settings: Output Coordinate System, Extent, Cell Size, and Snap Raster. The pattern of the back link raster would be significantly altered if it were resampled or reprojected, resulting in an incorrect path.

Syntax

Parameter	Explanation
inputDestinationRasterOrFeatures	An image service or feature service that identifies those locations from which the least-cost path is determined to the least costly source. If the input is an image service, the input consists of cells that have valid values (zero is a valid value), and the remaining cells must be assigned NoData.
inputDistanceAccumulationRaster	The input distance accumulation raster.
inputBackDirectionRaster	The name of the raster used to determine the path to return to a source via the least-cost path or the shortest path. For each cell in the back link or direction raster, a value identifies the neighbor that is the next cell on the path from the cell to a source cell.
outputPolylineName	The output feature service that will contain the least cost path.
destinationField (Optional)	The field that will be used to obtain values for the destination locations.
pathType (Optional)	Specifies the manner in which the values and zones on the input destination data will be interpreted in the cost path calculations. Best single—For all cells on the input destination data, the least-cost path will be derived from the cell with the minimum of the least-cost paths to source cells. Each zone—For each zone on the input destination data a least-cost path is determined. With this option, the least-cost path for each zone will begin at the cell with the lowest cost distance weighting in the zone. This is the default. Each cell—For each cell with valid values on the input destination data, a least-cost path is determined and saved on the output raster. With this option, each cell of the input destination data will be treated separately, and a least-cost path will be determined for each from cell.
createNetworkPaths (Optional)	There is no explanation for this parameter.
context (Optional)	There is no explanation for this parameter.

Code Samples

The following Python Window script demonstrates how to use the OptimalPathAsLine tool.

Calculates the optimal path from a source to a destination.

# Name: CalculateDistance_Ex_02.py
# Description: Calculates for each cell the Euclidean distance, direction and allocation
#              to the nearest source.
# Requirements: ArcGIS Image Server

# Import system modules
import arcpy

# Set local variables
inSourceData = 'https://MyPortal.esri.com/server/rest/services/Hosted/reccenter/ImageServer'
outDistanceName = "eucdistance"
maxDistance = "4000"
cellSize = "10"
outDirectionName = "eucdirect"
outAllocationName = "eurallocation"
allocationField = "dataid"


# Execute EucDistance
arcpy.CalculateDistance_ra(inSourceData, outDistanceName, maxDistance, cellSize, outDirectionName,
                           outAllocationName, allocationField)

OptimalPathAsLine

Title OptimalPathAsLine

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