| Sketch is a line-based art painting,the artist established the creative intent the first object of the painting to be analyzed,extracted from the painting lines,according to their own artistic characteristics of the abstract and stylized,and finally draw,Dimensional painting.To this end,this paper based on three-dimensional point cloud model,the three-dimensional sketch simulation method.The main innovative work is summarized as follows:(1)Introduces a method of extracting ridge valley from point cloud model.Using the traditional curvature threshold to determine the ridge valley algorithm,and then connect and optimize the ridge line,so that it can express some of the characteristics of point cloud model.(2)Obtain a 3D point cloud model contour extraction method.At the specific point of view,an edge contour extraction algorithm based on line of sight is proposed,and the outline of contour connection is summarized.A contour line connection algorithm is proposed to improve the external contour feature.(3)Designed a point cloud ridge line and contour line fusion method.In a point of view,since the scattered cloud has no topological structure and there is a gap between points and points,a point cloud visibility algorithm is introduced for the ridge line to make it visible at the back of the line of sight.Since the contour line is a two-dimensional pattern at a specific viewpoint,and the ridge line is a three-dimensional image based on the three-dimensional curvature threshold,a contour and ridge line integration algorithm is explored.(4)Design a model of line thickness diffusion.Aiming at the fused ridge line and contour line,an angle-based method of line thickness change is proposed to solve the thickness diffusion of lines under different bending degrees.At the same time,a method of line thickness change based on depth is proposed to solve the problem of line thickness diffusion at different depths.According to the two constructs the line model,lay the foundation for the drawing of the sketch.(5)A shadow change model based on line density is given.Under the specific illumination,a shadow region extraction algorithm is given.At the same time,it analyzes the density distribution of the real lines in the shadow area,and explores a line density algorithm.In order to depict the gradient brightness of the shaded area,a gray area variation algorithm is designed.Finally,the line model and shadow model fusion,drawing the effect of drawing. |
