This dataset displays the Vector Ruggedness Measure (VRM) for the DRECP study site and surrounding 12 km buffer at 270m resolution. This dataset was originally derived at 30m resolution, using the 30m NED, and run with a 9x9 (270m) neighborhood size. The resulting VRM dataset was projected to CA Albers Equal Area NAD83 and resampled to 270m resolution to match the DRECP statistical species distribution models.
The Vector Ruggedness Measure measures terrain ruggedness as the variation in three-dimensional orientation of grid cells within a neighborhood. Vector analysis is used to calculate the dispersion of vectors normal (orthogonal) to grid cells within the specified neighborhood. This method effectively captures variability in slope and aspect into a single measure.
Ruggedness values in the output raster can range from 0 (no terrain variaton) to 1 (complete terrain variation). Typical values for natural terrains range between 0 and about 0.4.
VRM was adapted from a method first proposed by Hobson (1972). VRM appears to decouple terrain ruggedness from slope better than current ruggedness indices, such as TRI or LSRI. See Sappington et al. 2007, for further details.
References:
Hobson, R.D. 1972. Surface roughness in topography: quantitative approach. Pages 221–245 in R. J. Chorley, editor. Spatial analysis in geomorphology. Harper and Row, New York, New York, USA.
Sappington, J.M., K.M. Longshore, and D.B. Thomson. 2007. Quantifiying Landscape Ruggedness for Animal Habitat Anaysis: A case Study Using Bighorn Sheep in the Mojave Desert. Journal of Wildlife Management. 71(5): 1419 -1426.
Link to paper: http://www.werc.usgs.gov/fileHandler.ashx?File=/Lists/Products/Attachments/3490/Sappington%20et%20al%20JWM%202007.pdf