Parameterized Design And Stylized Research Of Bas-relief Based On Normal Field

Relief is a sculpture caved on the fictile base surface with a bumpy shape.It combines light and perspective to generate a sense of space.As a kind of relief,the shape of the bas-relief is compressed,and the space occupied is small.It maintains feature details and reflects stereo perception.Therefore,its application scenarios are more extensive.The traditional way of making bas-relief mainly through the artists' handwork,or editing a 2D image to produce a 3D relief with software.Its main problem is a high production threshold and low production efficiency.With the development of 3D modeling software and 3D printing technology,the design of digital bas-relief based on the 3D model is becoming more and more mature.It gets the advantages of high efficiency,convenience,precision,intuition,and so on.It can remarkably improve the design efficiency and accuracy of the bas-relief.The design of digital bas-relief based on a 3D model is mainly compressing the3 D model as a height field.A large number of feature details are lost in the compression process,and the layered feeling and the stereoscopic effect are greatly reduced.In addition,the production of bas-relief need to determine the direction of mapping of 3D model firstly,so that it can only get a bas-relief under a certain view with fixed style and a single pattern.It can't meet the individualized needs of people's aesthetic preferences.In view of the above problems,the following solutions are proposed in this paper:(1)In this paper,we propose a parameterization technology to produce bas-relief based on the normal field.We construct a normal domain which contains the feature details by graded smoothing of focus regions and parameterization method.This realizes the generation of bas-relief with the feature preservation,which not only reasonably maintains the highlight of the feature details,but also effectively enhances the layered feeling and the stereoscopic effect.The initial input of the algorithm is a3 D mesh model.Firstly,the region of focus is graded according to the mesh saliency and mesh distortion,and different degrees of smoothing is applied to the regions with various levels.Then,the feature details are extracted from the difference of normaloffset before and after mesh smoothing.We transplant and rebuild the feature details to the base plane of smoothing mesh parameterization to construct a normal domain.Finally,the height field is reconstructed from the normal field to generate a bas-relief with the feature details.(2)In this paper,we propose an approach of bas-relief stylization based on the normal field.By separating the feature information of different frequencies on the bas-relief model and editing on the normal domain,this method can edit bas-relief with different styles,not only control the feature details of the model surface naturally,but also get all kinds of styles that are different from the initial bas-relief.The initial input of the algorithm is the height field of bas-relief.First,Gaussian filters are used to extract the high-frequency information and low-frequency information from the initial height image.They represent the details and the overall shape of the bas-relief.Next,the normal information of different frequency is obtained by a bilateral surface fitting method.Then,we use stereographic mapping of different projections to edit the normal of these two frequency fields.Finally,through the linear combination of Laplacian,the least square method is used to reconstruct the height field to obtain various styles of bas-relief.For the shortcomings in the design of bas-relief,this paper puts forward a parameterized design solution of bas-relief making and a stylized design solution of bas-relief editing,which provides a new method and opens up a new way for the development of bas-relief.