Creates a Styled Layer Description (SLD) file, that can be attached to a spatial layer contributed to GeoServer. It writes the "sp.pallete"
object (legend entries, titles and colors) to an external file.
# S4 method for SpatialMetadata
metadata2SLD(obj, …)
object of class "SpatialMetadata"
other arguments
The structure of the SLD file is determined by the object class (Point, Polygon, SpatialPixels).