VfInverseLinear (arcpy.sa)

Resumen

Defines the relationship between the vertical cost factor and the vertical relative moving angle through an inverse linear function.

Ilustración

VfInverseLinear vertical factor for the PathDistance functions.

Debate

The VfInverseLinear object is used in the Spatial Analyst tools Path Distance, Path Distance Allocation, and Path Distance Back Link.

The vertical factor (VF) object defines the relationship between the vertical cost factor and the vertical relative moving angle (VRMA).

VF defines the vertical difficulty encountered in moving from one cell to the next.

VRMA identifies the slope angle between the FROM or processing cell and the TO cell.

The VFs are determined by the inverse values from a straight line in the VRMA-VF coordinate system. The line intercepts the y-axis, equitable to the VF factor, the value associated with the zeroFactor. The slope of the line can be identified if specified with the slope argument.

Sintaxis

VfInverseLinear ({zeroFactor}, {lowCutAngle}, {highCutAngle}, {slope})

Parámetro	Explicación	Tipo de datos
zeroFactor	The zeroFactor will be used to position the y-intercept of the inverse linear function. (El valor predeterminado es 1.0)	Double
lowCutAngle	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity. (El valor predeterminado es -45.0)	Double
highCutAngle	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity. (El valor predeterminado es 45.0)	Double
slope	Identifies the slope of the straight line in the VRMA-VF coordinate system. Slope is specified as the rise/run. For example, a 30-degree slope is 1/30, specified as 0.03333 (rise/run: 1 VF on the y axis / 30 degrees on the x axis); a -45-degree slope as -0.02222. (El valor predeterminado es -0.022222)	Double

Propiedades

Propiedad	Explicación	Tipo de datos
zeroFactor (Lectura y escritura)	The zeroFactor is used to position the y-intercept for the vertical factor class.	Double
lowCutAngle (Lectura y escritura)	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity.	Double
highCutAngle (Lectura y escritura)	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity.	Double
slope (Lectura y escritura)	Identifies the slope of the straight line in the VRMA-VF coordinate system. Slope is specified as the rise over the run. For example, a 30-degree slope is 1/30, specified as 0.03333 (rise/run: 1 VF on the y axis / 30 degrees on the x axis); a 90-degree slope as 0.011111.	Double

Ejemplo de código

VfInverseLinear example 1 (Python window)

Demonstrates how to create a VfInverseLinear class and use it in the PathDistance tool within the Python window.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
myVerticalFactor = VfInverseLinear(1.0, -45, 45, -0.02222)
outPathDist = PathDistance("source.shp", "costraster", "", "", "", "",
                           myVerticalFactor)
outPathDist.save("C:/sapyexamples/output/pathdistvfil")

VfInverseLinear example 2 (stand-alone script)

Performs a PathDistance analysis using the VfInverseLinear class.

# Name: VfInverseLinear_Ex_02.py
# Description: Uses the VfInverseLinear object to execute the PathDistance tool.
# Requirements: Spatial Analyst Extension

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inSourceData = "source.shp"
inCostRaster = "costraster"

# Create the VfInverseLinear Object
zeroFactor = 1.0
lowCutAngle = -45
highCutAngle = 45
slope = -0.02222
myVerticalFactor = VfInverseLinear(zeroFactor, lowCutAngle, highCutAngle,
                                    slope)

# Check out the ArcGIS Spatial Analyst extension license
arcpy.CheckOutExtension("Spatial")

# Execute PathDistance
outPathDist = PathDistance(inSourceData, inCostRaster, "", "", "", "",
                           myVerticalFactor)

# Save the output 
outPathDist.save("C:/sapyexamples/output/pathdistvfil2")