VfSecCos

摘要

Defines the relationship between the vertical cost factor and the vertical relative moving angle (VRMA) through a secant/cosine function. If the VRMA is negative the vertical factor is defined by a secant function, and if the VRMA is nonnegative the vertical factor is defined by a cosine function.

插图

VfSecCos vertical factor for the PathDistance functions.

讨论

The VfSecCos 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.

When the VRMA is a negative degree value, the VF is determined by the cosine function of the VRMA. If the VRMA is a positive degree value, the VF is determined by the secant function of the VRMA.

语法

VfSecCos ({lowCutAngle}, {highCutAngle}, {secPower}, {cosPower})

参数	说明	数据类型
lowCutAngle	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity (默认值为 -90.0)	Double
highCutAngle	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity. (默认值为 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 (默认值为 1.0)	Double
cosPower	The power to which the values in the cosine VRMA function will be raised. The VF is determined by: VF = cos(VRMA)power (默认值为 1.0)	Double

属性

属性	说明	数据类型
lowCutAngle （可读写）	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity.	Double
highCutAngle （可读写）	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity.	Double
secPower （可读写）	The power to which the values in the secant VRMA function will be raised. The VF is determined by: VF = sec(VRMA)power	Double
cosPower （可读写）	The power to which the values in the cosine VRMA function will be raised. The VF is determined by: VF = cos(VRMA)power	Double

代码示例

VfSecCos example 1 (Python window)

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

VfSecCos example 2 (stand-alone script)

Performs a PathDistance analysis using the VfSecCos class.

# Name: VfSecCos_Ex_02.py
# Description: Uses the VfSecCos 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 VfSecCos Object
lowCutAngle = -90
highCutAngle = 90
secPower = 1
cosPower = 1
myVerticalFactor = VfSecCos(lowCutAngle, highCutAngle, secPower, cosPower)

# 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/pathdistvfsc2")