Another advantage is that geometric properties of the curve are easily determined from a particular level set of the surface . For example, the normal vector for any point on the curve C is given by:

近红外光谱标准正态变量变换处理方法，主要是消除固体颗粒大小，表面散射以及光程变化对漫反射光谱的影响。-Near infrared spectrum standard normal variable transform processing method, mainly eliminate the solid particle size, surface scattering and the change of optical path of diffuse reflection spectra.