The high resolution mesh tessellation method using PN-triangle (Point Normal – triangle) derived from the low resolution mesh triangle is widely used because it does not require the adjacent triangle information. With this PN-triangle tessellation method, the method to further subdivide triangles close to the silhouette was also presented. However, the previous method produces the extreme case where the tessellation factor will be zero when a triangle is far away from the silhouette. In this paper, unlike the previous method, ① the modified method to smoothly increase the tessellation factor as close to the silhouette is proposed. ② Also the method to increase the tessellation factor as close the view and away to the silhouette is proposed. ③ The modified method to increase the tessellation factor as the size of primitive is also proposed. The proposed method is verified by the experimental simulation.