We used unit vectors of the parametric surface cells as an important parameter to achieve the surface evolution algorithm.Instead of the normal vectors of facet cells

Gauss integration is adopted to calculate the normal vectors of the surface cells

so as to determine the evolvement directions of the cells.The simulation results of this algorithm were 3-D visible of variable perspective.If a physical model of given fabrication is provided

it can be applied to other processes with surface evolution direction dependence.Some isotropic etching simulations were performed as examples

and the results indicate the accurate simulated surface.