AdjSD                   Calculates standard deviation of bathymetry (a
                        measure of rugosity) adjusted for slope
BPI                     Calculates Bathymetric Position Index
DMV                     Calculates Difference from Mean Value (DMV)
DirSlp                  Directional Slope
Pfit                    Calculates multiscale slope and aspect using a
                        local planar fit.
Qfit                    Calculates multiscale slope, aspect, curvature,
                        and morphometric features using a local
                        quadratic fit
RIE                     Calculates Roughness Index-Elevation
RelPos                  Calculates Relative Position of a focal cell
SAPA                    Calculates surface area to planar area rugosity
SlpAsp                  Multiscale Slope and Aspect
SurfaceArea             Calculates surface area of a DTM
TPI                     Calculates Topographic Position Index
VRM                     Implementation of the Sappington et al., (2007)
                        vector ruggedness measure
annulus_window          Creates annulus focal window
circle_window           Creates circular focal window
classify_features_ff    Helper function factory to classify
                        morphometric features
erupt                   Create georeferenced version of R's built in
                        volcano dataset
explore_terrain         Interactive Shiny app to look at terrain
                        attributes
kmax                    Calculate max curvature
kmean                   Calculate mean curvature
kmin                    Calculate min curvature
knc                     Calculate normal contour curvature
kns                     Calculate normal slope line curvature
ku                      Calculate unsphericity curvature
outlier_filter          Helper function to filter outliers from
                        regression parameters using interquartile range
tgc                     Calculate contour geodesic torsion
