1. A method of converting an explicit definition of a geometric object located in a prescribed space to a level set which implicitly defines said geometric object, the method comprising: dividing the prescribed space into a grid of voxels, each voxel comprising a unit of the prescribed space; casting rays in plural directions to obtain plural distance votes associated with each voxel in which each distance vote represents a distance from the voxel, through the prescribed space, to the geometric object in one of said plural directions of the rays; assigning a magnitude value to each voxel by selecting the distance vote associated with that voxel which is lowest in magnitude; determining if each voxel is either inside or outside of the geometric object in the prescribed space; and assigning a sign value to each voxel, the sign value being either a positive sign or a negative sign in which each of the signs is representative of a sign condition of the voxel being either inside or outside of the geometric object.