A computer system for generating an estimated volume of activation (VOA) for a stimulation, the system comprising: a computer processor configured to: for each of a plurality of neural elements that are in a vicinity of a leadwire: determine a respective threshold activation value, wherein the determination of the respective threshold activation value includes: determining two or more parameters characterizing an electrical profile along a trajectory of the respective neural element; matching the two or more parameters to two or more of a plurality of parameters each stored in association with a respective threshold activation value; and obtaining the one or more respective threshold activation values associated with the two or more of the plurality of parameters; and determine whether a user-input stimulation value to be applied to the leadwire meets the respective threshold activation value of the respective neural element; and generate a surface structure corresponding to those of the neural elements whose respective threshold activation values have been determined to be met by the user-input stimulation value. for each of a plurality of neural elements that are in a vicinity of a leadwire: determine a respective threshold activation value, wherein the determination of the respective threshold activation value includes: determining two or more parameters characterizing an electrical profile along a trajectory of the respective neural element; matching the two or more parameters to two or more of a plurality of parameters each stored in association with a respective threshold activation value; and obtaining the one or more respective threshold activation values associated with the two or more of the plurality of parameters; and determine whether a user-input stimulation value to be applied to the leadwire meets the respective threshold activation value of the respective neural element; and determine a respective threshold activation value, wherein the determination of the respective threshold activation value includes: determining two or more parameters characterizing an electrical profile along a trajectory of the respective neural element; matching the two or more parameters to two or more of a plurality of parameters each stored in association with a respective threshold activation value; and obtaining the one or more respective threshold activation values associated with the two or more of the plurality of parameters; and determining two or more parameters characterizing an electrical profile along a trajectory of the respective neural element; matching the two or more parameters to two or more of a plurality of parameters each stored in association with a respective threshold activation value; and obtaining the one or more respective threshold activation values associated with the two or more of the plurality of parameters; and determine whether a user-input stimulation value to be applied to the leadwire meets the respective threshold activation value of the respective neural element; and generate a surface structure corresponding to those of the neural elements whose respective threshold activation values have been determined to be met by the user-input stimulation value. <EOS>