Calculates specific paths between known sources and known destinations.
One example application of this tool to find the travel cost to get to certain destinations.
The Determine Travel Cost Paths To Destinations tool produces an output raster that records the least-cost path or paths from selected locations to the closest source cell defined within the accumulative cost surface, in terms of cost distance.
Running Calculate Travel Cost is generally required prior to running Determine Travel Cost Paths To Destinations to create the input cost distance and back link image services. These are mandatory input image services to Determine Travel Cost Paths To Destinations.
Each least-cost path is assigned a value when encountered in the scanning process. The ending cell on the original source (from which the cost distance and back link were derived) of a cost path receives one, the first path receives three, the second four, and so on. The value two is reserved for the merged portion of paths that have portions of a common cost path.
When the input destination data is an image service, the set of destination cells consists of all cells in the input image service or feature destination data that have valid values. Cells that have NoData values are not included in the source set. The value zero is considered a legitimate destination.
When the source input is a feature service, by default, the first valid available field will be used. If no valid fields exist, the ObjectID field (for example, OID or FID) will be used.
When multiple paths merge and follow the remaining distance back to a source on the same route, the segment where the two paths travel together is assigned the value 2. The merged portion of the path cannot be assigned the value of one of the paths, since the merged portion belongs to both routes.
Determine Travel Cost Paths To Destinations will ignore the Cell size environment setting and use the cell size of the Input cost backlink raster for the output raster. The pattern of the back link raster would be seriously altered if it were resampled to a different resolution. To avoid any confusion, the cell size should not be set when using this tool.
Determine Travel Cost Paths To Destinations can also be used to derive the path of least resistance down a digital elevation model (DEM). In this case, use the DEM for the Input cost distance raster and the output from the Flow Direction tool for the Input cost backlink raster. Valid flow direction raster values are 1, 2, 4, 8, 16, 32, 64, and 128; valid values in the back link raster are 1, 2, 3, 4, 5, 6, 7, and 8. Both of these image services are acceptable.
When the input destination data is feature, it must contain at least one valid field.
| Parameter | Explanation |
|---|---|
| inputDestinationRasterOrFeatures |
An image service or feature service that identifies the cells 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. |
| inputCostDistanceRaster |
The name of a cost distance image service to be used to determine the least-cost path from the destination locations to a source. The cost distance raster is usually created with the Calculate Travel Cost tool. The cost distance raster stores, for each cell, the minimum accumulative cost distance over a cost surface from each cell to a set of source cells. |
| inputCostBacklinkRaster |
The name of a cost back link raster used to determine the path to return to a source via the least-cost path. For each cell in the back link raster, a value identifies the neighbor that is the next cell on the least accumulative cost path from the cell to a single source cell or set of source cells. |
| outputName |
The name of the output travel cost paths raster service. The default name is based on the tool name and the input layer name. If the layer already exists, you will be prompted to provide another name. |
| destinationField (Optional) |
A field on the destination layer that holds the values that define each destination. Input feature service must contain at least one valid field. |
| pathType (Optional) |
Defines the manner in which the values and zones on the input destination data will be interpreted in the cost path calculations.
|
DetermineTravelCostPathsToDestinations example 1 (Python window)
This example calculates the travel cost to destinations.
import arcpy
arcpy.DetermineTravelCostPathstoDestinations_ra(
"https://myserver/rest/services/sources/ImageServer",
"https://myserver/rest/services/costsurface/ImageServer",
"https://myserver/rest/services/backlinkras/ImageServer",
"outpath", "destField", "EACH_ZONE")
DetermineTravelCostPathsToDestinations example 2 (stand-alone script)
This example calculates the travel cost to destinations.
#-------------------------------------------------------------------------------
# Name: DetermineTravelCostPathstoDestinations_Ex_02.py
# Description: Calculates the optimum travel cost path.
# Requirements: ArcGIS Image Server
# Import system modules
import arcpy
# Set local variables
inputSourceLayer =
'https://MyPortal.esri.com/server/rest/services/Hosted/sources/ImageServer'
inputCostLayer =
'https://MyPortal.esri.com/server/rest/services/Hosted/costraster/ImageServer'
inputBackLinkLayer =
'https://MyPortal.esri.com/server/rest/services/Hosted/backlinkras/ImageServer'
outputName = 'outTravelPathsRaster'
destField = 'dest1'
pathType = 'BEST_SINGLE'
arcpy.DetermineTravelCostPathstoDestinations_ra(inputSourceLayer, inputCostLayer,
inputBackLinkLayer, outputName,
destField, pathType)
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