An overview of vertical factor classes

The vertical factors (VFs) classes define the difficulty of moving from one cell to another while accounting for the vertical elements that may affect the movement. The Path Distance tool uses the vertical factor object to determine the vertical factor. To determine the VF for moving from one cell to the next, the slope between the FROM cell and the TO cell is calculated from the values defined in the input vertical factor raster. The resulting slope is the vertical relative moving angle (VRMA), which is plotted on the vertical factor graph to identify the value used for the vertical factor in the path distance calculations for the cell-to-cell movement. This vertical factor establishes the vertical factor from the center of the starting cell to the center of the destination cell. The larger the vertical factor, the more difficult the movement.

The vertical relative moving angle is calculated using the formula rise/run, with the z-values of the TO and FROM cell established by the input vertical factor raster. The VRMA is specified in degrees. The range of VRMAs is from -90 to +90 degrees, compensating for both positive and negative slopes. The VRMA value is then plotted on the vertical factor graph to obtain the vertical factor that will be used in the calculations that determine the cost to reach the TO cell. The resolution of the VRMAs is 0.25 degree.

VfBinary	Defines the relationship between the vertical cost factor and the vertical relative moving angle through a binary function. If the vertical relative moving angle is greater than the low-cut angle and less than the high-cut angle, the vertical factor is set to the value associated with the zero factor; otherwise it is infinity.
VfCos	Defines the relationship between the vertical cost factor and the vertical relative moving angle through a cosine function.
VfCosSec	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.
VfInveseLinear	Defines the relationship between the vertical cost factor and the vertical relative moving angle through an inverse linear function.
VfLinear	Defines the relationship between the vertical cost factor and the vertical relative moving angle through a linear function.
VfSec	Defines the relationship between the vertical cost factor and the vertical relative moving angle through a secant function.
VfSecCos	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.
VfSymInverseLinear	Defines the relationship between the vertical cost factor and the vertical relative moving angle (VRMA) through a symmetrical inverse linear function in either the negative or positive side of the VRMA, respectively. The two linear functions are symmetrical with respect to the VF (y) axis.
VfSymLinear	Defines the relationship between the vertical cost factor and the vertical relative moving angle (VRMA) through a symmetrical linear function in either the negative or positive side of the VRMA, respectively. The two linear functions are symmetrical with respect to the VF (y) axis.
VfTable	Defines the relationship between the vertical cost factor and the vertical relative moving angle with a vertical-factor graph identifying the vertical factor specified by a table file.

Tools that use vertical factor objects

PathDistancePathDistanceAllocationPathDistanceBackLink