VfCosSec

Disponible con una licencia de Spatial Analyst.

Resumen

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

Ilustración

Graph of the cosine secant vertical factor.

Debate

This object is used in the Distance Accumulation and Distance Allocation Spatial Analyst tools, as well as the Path Distance, Path Distance Allocation, and Path Distance Back Link Legacy Distance tools.

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.

Sintaxis

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

Parámetro	Explicación	Tipo de datos
lowCutAngle	The VRMA degree defining the lower threshold, below which (less than) the VFs are set to infinity. (El valor predeterminado es -90.0)	Double
highCutAngle	The VRMA degree defining the upper threshold, beyond which (larger than) the VFs are set to infinity. (El valor predeterminado es 90.0)	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 (El valor predeterminado es 1.0)	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 (El valor predeterminado es 1.0)	Double

Propiedades

Propiedad	Explicación	Tipo de datos
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
cosPower (Lectura y escritura)	The power to which the values in the cosine VRMA function will be raised. The VF is determined by: VF = cos(VRMA)power	Double
secPower (Lectura y escritura)	The power to which the values in the secant VRMA function will be raised. The VF is determined by: VF = sec(VRMA)power	Double

Muestra de código

VfCosSec example 1 (Python window)

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

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
myVerticalFactor = VfCosSec(-90, 90, 1, 1)
outDistAccum = DistanceAccumulation("Source.shp", "", "elev.tif",
                                   "cost.tif", "elev.tif",
                                    myVerticalFactor)
outDistAccum.save("C:/sapyexamples/output/distAccumVfCS.tif")

VfCosSec example 2 (stand-alone script)

Performs a DistanceAccumulation analysis using the VfCosSec class.

# Name: VfCosSec_Ex_02.py
# Description: Uses the VfCosSec object to run the 
#              DistanceAccumulation 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.tif"
inElevation = "elev.tif"


# Create the VfCosSec Object
lowCutAngle = -90
highCutAngle = 90
cosPower = 1
secPower = 1
myVerticalFactor = VfCosSec(lowCutAngle, highCutAngle, cosPower, secPower)

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

# Execute PathDistance
outDistAccum = DistanceAccumulation(inSourceData, "", inElevation,
                                    inCostRaster, inElevation,
                                    myVerticalFactor)

# Save the output 
outDistAccum.save("C:/sapyexamples/output/distaccumvfCS2.tif")