| AdjSD | Calculates standard deviation of bathymetry (a measure of rugosity) adjusted for slope | 
| annulus_window | Creates annulus focal window | 
| BPI | Calculates Bathymetric Position Index | 
| circle_window | Creates circular focal window | 
| classify_features_ff | Helper function factory to classify morphometric features | 
| DirSlp | Directional Slope | 
| DMV | Calculates Difference from Mean Value (DMV) | 
| 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 | 
| 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 | 
| RelPos | Calculates Relative Position of a focal cell | 
| RIE | Calculates Roughness Index-Elevation | 
| SAPA | Calculates surface area to planar area rugosity | 
| SlpAsp | Multiscale Slope and Aspect | 
| SurfaceArea | Calculates surface area of a DTM | 
| tgc | Calculate contour geodesic torsion | 
| TPI | Calculates Topographic Position Index | 
| VRM | Implementation of the Sappington et al., (2007) vector ruggedness measure |