VfSec (arcpy.sa)

Récapitulatif

Defines the relationship between the vertical cost factor and the vertical relative moving angle through a secant function.

Illustration

VfSec vertical factor for the PathDistance functions.

Discussion

The VfSec 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 VF is determined by the secant function of the VRMA.

Syntaxe

VfSec ({lowCutAngle}, {highCutAngle}, {secPower})

Paramètre	Explication	Type de données
lowCutAngle	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity. (La valeur par défaut est -90.0)	Double
highCutAngle	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity. (La valeur par défaut est 90.0)	Double
secPower	The power to which the values in the secant VRMA function will be raised. The VF is determined by: VF = sec(VRMA)power (La valeur par défaut est 1.0)	Double

Propriétés

Propriété	Explication	Type de données
lowCutAngle (Lecture/écriture)	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity.	Double
highCutAngle (Lecture/écriture)	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity.	Double
secPower (Lecture/écriture)	The power to which the values in the secant VRMA function will be raised. The VF is determined by: VF = sec(VRMA)power	Double

Exemple de code

VfSec example 1 (Python window)

Demonstrates how to create a VfSec 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 = VfSec(-90, 90, 1)
outPathDist = PathDistance("source.shp", "costraster", "","", "", "",
                           myVerticalFactor)
outPathDist.save("C:/sapyexamples/output/pathdistvfs")

VfSec example 2 (stand-alone script)

Performs a PathDistance analysis using the VfSec class.

# Name: VfSec_Ex_02.py
# Description: Uses the VfSec 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 VfSec Object
lowCutAngle = -90
highCutAngle = 90
secPower = 1
myVerticalFactor = VfSec(lowCutAngle, highCutAngle, secPower)

# 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/pathdistvfs2")