Burrough, P. A., and McDonell, R. A., 1998. Principles of Geographical Information Systems (Oxford University Press, New York)
spatial(x, slope = TRUE, aspect = TRUE)
| x | A matrix for spatial data with row for longitude and column for latitude. dimnames must be specified for values of longitude and latitude |
|---|---|
| slope | Logical, whether return slope |
| aspect | Logical, whether return aspect |