NAME gr_surfacenormals - a GRToolbox module DESCRIPTION Calculates the normal vectors of a surface.. SYNOPSIS: -[closed closedu closedv distance scale h o v noc nof now skip f m c e i s l] -help For help on all options. Special Options: -closed Assume, that the curves are closed. -distance float Distance between curve and normal curve. -scale float Scale factor for length of normals.