1. A method of a volume of activation (VOA) providing machine to provide a VOA of a stimulation electrode leadwire, comprising: plotting, by a processor of the machine, first electric values at anatomical locations for a set of stimulation parameter settings; determining, by the processor, a threshold for the set of stimulation parameter settings by application of a threshold function that outputs the threshold based on function input variables that include a pulse width, amplitude, and impedance of the stimulation parameter settings; based on the determined threshold, determining, by the processor, a three dimensional surface of an area that includes one of (a) those of the plotted first electric values that meet the threshold and (b) second electric values corresponding to a subset of the plotted first values and that meet the threshold; and outputting, by the machine, the area as a VOA.