[R] vector field from a 3D scalar field

[Waichler, Scott R]

I have a 3D field of a scalar variable (x, y, z, value).  Is there a way to generate a vector field from this data--gradient at defined points?  I found the rasterVis package for 2D data, but as yet nothing for 3D data.

Thanks,
Scott Waichler
Pacific Northwest National Laboratory
Richland, WA
scott.waichler at pnnl.gov