v3_Utilitiy Create Walkability Cost Raster

Create Walkability Cost Raster

Available with Spatial Analyst license.

Summary

Generates a cost surface raster for input into the Pedestrian Access and Availability tool.

Usage

Multiple inputs can be supplied for both the Walkable features and Impassable features. ons is not supported in this release.
NOTE: For the most accurate results and shortest processing times, it is highly recommended that all input layers be in the same spatial reference.
NOTE: Enabling the Parallel Processing Factor environment can improve computation time for several ATtILA tools, but we have detected, on rare occasions, doing so can lead to spurious results. As a precaution, ATtILA will disable the Parallel Processing Factor environment for this tool. We hope to return this choice to the user once the impact on operational speed and accuracy of swapping geoprocessing tools with their pairwise counterparts has been assessed.
Final output is written to the location specified in the Output table parameter. The Output table may be saved as a File Geodatabase Table, or a dBASE Table.
- NOTE: For most consistent results, it is highly recommended that tool output be saved to a file geodatabase.
- When saving as a File Geodatabase Table, no extension is necessary for the Output table name. The output location must be a file geodatabase.
- When saving as a dBASE Table, include the .dbf extension in the Output table name. dBASE tables may not be saved in a file geodatabase.
It is recommended that the extent and cell size of the Snap raster match the desired cell size and extent of the Pedestrian Access and Availability tool's Output raster.
In Additional Options, the user may elect to 'Retain Intermediate Layers Generated During Metric Processing', and/or 'Record Process Steps Taken During Metric Calculation'.
- Retain Intermediate Layers Generated During Metric Calculation
  - Choosing INTERMEDIATES retains several of the key intermediate products (e.g., rasters, feature classes, tables) used to generate the final tool output. By examining the intermediate products, the user can gain a better understanding how the metric is calculated. The following intermediate products are listed in the general order they are generated:
    - cwcr_Walk_Line_Merge_# (vector) - A vector feature class created by merging all line features found in Walkable features Only if more than one line feature layers are input into Walkable features.
    - cwcr_Walk_Raster_Line_# (raster) - Only if one or more line feature layers are provided in Walkable features.
    - cwcr_Walk_Poly_Merge_# (vector) - Only if more than one polygon feature layers are provided in Walkable features.
    - cwcr_Walk_Raster_Polygon_# (raster) - Only if one or more polygon feature layers are provided in the Walkable features. The vector converted to raster is either the single input polygon layer or the merged polygon layer
    - cwcr_Walk_Raster_# (raster) -
    - cwcr_Impass_Line_Merge_# (vector) - Only if more than one line feature layers are input into the Impassable features
    - cwcr_Impass_Raster_Line_# (raster) - Only if one or more impassable line features are supplied
    - cwcr_Impass_Poly_Merge_# (vector) - Only if more than one impassable polygon feature layers are supplied
    - cwcr_Impass_Raster_Polygon_# (raster) - Only if a polygon impassable feature layer is supplied
    - cwcr_Impass_Raster_# (raster) -
    - NOTE: To ensure unique filenames, intermediate filenames are typically generated using the CreateScratchName ArcPy function. This function provides a unique name for the intermediate product by appending a number to a filename prefix. The number starts at 0 and is incremented until a unique filename for the output workspace is found. The generated number is represented in this manual by the hashtag (#) symbol.
    - NOTE: The appended number may not be the same for all intermediate products saved during a tool run. Running a tool with different input options can result in different intermediate products being produced. If a tool is run more than once using the same output workspace, different number suffixes may be generated depending on the files already present in the output workspace.
  - Intermediate products are saved to one of the following locations:
    - When the Output table is saved as a File Geodatabase Table, intermediate products are placed in the same file geodatabase.
    - When the Output table is saved as a dBASE Table, a file geodatabase named "attilaScratchWorkspace" is automatically generated in the same output location specified for the Output table. Intermediate products are placed in the attilaScratchWorkspace file geodatabase.
    - NOTE: ATtILA will report the location of the saved intermediate products in the Tool Details' Messages section.
- Record Process Steps Taken During Metric Calculation
  - Choosing LOGFILE will generate a text file containing information on system setup, tool inputs, parameter selections, script operations, and any encountered error or warning messages.
  - Log files will be named, [Output table]_[date_time].txt, with the date represented as YYYYMMDD and time as hh_mm_ss.
  - Where the log file is saved is dependent on the Current Workspace environment setting:
    - When the Current Workspace is a geodatabase, the log file will be located in the folder that contains that workspace.
    - When the Current Workspace is a folder, the log file will be located in that folder.
    - NOTE: In ArcGIS Pro, the default value for the Current Workspace environments is the project default geodatabase.
    - NOTE: ATtILA will report the name and location of the log file in the Tool Details' Messages section.

Syntax

CWCR (Walkable_features, {Impassable_features}, Maximum_travel_distance, Walk_value, Base_value, Output_cost_raster, Cost_raster_cell_size, Snap_raster, {Select_options})

Parameter	Explanation	Data Type
Walkable_features	The vector polygon and/or polyline Feature Layers that define walkable routes. If selected features exist in the input feature layers, the user can elect to use only those features for generating the Output cost raster.	Multiple Value
Impassable_features (Optional)	The vector polygon and/or polyline Feature Layers that define impassable features. If selected features exist in the input feature layers, the user can elect to use only those features for generating the Output cost raster.	Multiple Value
Maximum_travel_distance	The distance where further travel is not possisble. This value is used along with the Cost raster cell size to define the Output cost raster's impassable value in the Output cost raster. Impassable value = (Maximum walking distance / Cost raster cell size) rounded up to the nearest integer. The value units must be a positive integer value.	Long
Walk_value	The cost of traveling through a walkable cell. The value defines the cost of least resistance. Value units must be a positive integer value.	Long
Base_value	The cost of traveling through a walking-resistant cell. The value defines the cost of difficult, but passable, resistance. Value units must be a positive integer value.	Long
Output_cost_raster	The output cost surface raster. It is always an integer raster.	Raster Dataset
Cost_raster_cell_size	The cell size of the output raster that will be created. Units use the linear unit of the geoprocessing outputCoordinateSystem environment setting. If no outputCoordinateSystem is set, the linear unit of the Snap raster's is used.	Double
Snap_raster	The raster that the cell alignment of the Output cost raster will be set to. The Snap raster's linear unit will be used for the Cost raster cell size if no outputCoordinateSystem environment is set.	Raster Layer
Select_options	Tool options available to provide additional information: Retain Intermediate Layers Generated During Metric Calculation - Saves key intermediate products (e.g., rasters, feature classes, tables) used to generate the final tool output. Record Process Steps Taken During Metric Calculation - Saves a log file containing information on tool inputs, selections, and operations.	Multiple Value

Code Samples

Create Walkability Cost Raster example 1 (Python window)

This example generates a cost surface raster where the cell values represent that cell's resistance to movement (1 = easy, 10 = resistant, and 80 = impassable). One line feature layer was entered as input for walkable pathways, while barriers to movement were represented by two line and one polygon feature layers.

import arcpy
from arcpy.sa import *
arcpy.ImportToolbox(r"D:\Destination Folder\ATtILA v{#}.tbx")
from ATtILA2 import metric

Walkable_features = "Roads_Walkable",
Impassable_features = "Roads_NonWalkable;Water_Lines;Water_Polygons",
Maximum_travel_distance = 800,
Walk_value = 1,
Base_value = 10,
Output_cost_raster = r"D:\pyexamples\results.gdb\WalkabilityRaster",
Cost_raster_cell_size = 10,
Snap_raster = r"D:\pyexamples\data.gdb\NLCD_2016",
Select_options = ['INTERMEDIATES  -  Retain Intermediate Layers Generated During Metric Calculation','LOGFILE  -  Record Process Steps Taken During Metric Calculation']

arcpy.ATtILA.CWCR(Walkable_features,
				  Impassable_features,
				  Maximum_travel_distance,
				  Walk_value,
				  Base_value10,
				  Output_cost_raster,
				  Cost_raster_cell_size,
				  Snap_raster,
				  Select_options)

Create Walkability Cost Raster example 2 (Tool Details Messages)

This is a sample capture of the geoprocessing messages generated during a typical tool run. It is provided here to assist in the understanding of the tool's processing steps.


Start Time: Day, Month DD, YYYY hh:mm:ss AM/PM
Created log file: workspace path\\filename
Started: YYYY-MM-DD hh:mm:ss Setting up environment variables
Intermediates are stored in this directory: workspace path
[YYYY-MM-DD hh:mm:ss] Using NLCD_2016's extent for geoprocessing steps.
[YYYY-MM-DD hh:mm:ss] Using NLCD_2016's spatial reference for geoprocessing steps: Albers_Conical_Equal_Area
[YYYY-MM-DD hh:mm:ss] Processing Walkability features
[YYYY-MM-DD hh:mm:ss] Converting Roads_Walkable to raster. Intermediate: cwcr_Walk_Raster_Line_1
[YYYY-MM-DD hh:mm:ss] Setting converted raster cell values to 1 where features exist. Everywhere else will be set to 10. Intermediate: cwcr_Walk_Raster_1
[YYYY-MM-DD hh:mm:ss] Impass Value = 80. Calculated as (Maximum walking distance / Cost raster cell size) rounded up to the nearest integer
[YYYY-MM-DD hh:mm:ss] Processing Impassable features
[YYYY-MM-DD hh:mm:ss] Merging 2 line features from input features. Intermediate: cwcr_Impass_Line_Merge_1
[YYYY-MM-DD hh:mm:ss] Converting cwcr_Impass_Line_Merge_1 to raster. Intermediate: cwcr_Impass_Raster_Line_1
[YYYY-MM-DD hh:mm:ss] Converting Water_Polygons to raster. Intermediate: cwcr_Impass_Raster_Polygon_1
[YYYY-MM-DD hh:mm:ss] Combining converted rasters and setting output cell values to 80 where features exist. Everywhere else will be set to 10. Intermediate: cwcr_Impass_Raster_1
[YYYY-MM-DD hh:mm:ss] Combining the Walkable raster with the Impassable raster for final output
Log file closed
Succeeded at Day, Month DD, YYYY hh:mm:ss AM/PM (Elapsed Time: ##.## units)