1. A system for a neurostimulation device having a stimulation lead, comprising: at least one processor configured for estimating at a plurality of spatial points a respective plurality of electrical field vectors resulting from the stimulation lead operating in accordance with a set of stimulation parameters, determining an amplitude of each electrical field vector and an angle between each electrical field vector and a vector aligned with an axis of the stimulation lead, and estimating a tissue of volume activation about the stimulation lead based on the determined amplitude and angle of each electrical field vector.