Adaptive Gaussian Filter-based Relief Extraction From 3D Model

With the rapid development of computer technology,the use of computer graphics technology to protect the cultural relics has become a trend.To carry out the digital storage of the cultural relics can not only protect the cultural relics effectively,but also make the commercial value of the cultural relics.Each piece of cultural relics has a lot of precious information,such as shape,texture,color and so on.In this paper,these precious information are referred to as cultural relics material.For some cultural relics,storing their information by two-dimensional digital image is not enough.On the other hand,we are able to use three-dimensional model to store their information.There are some reliefs in the surface of the three-dimensional model of the cultural relics.In this paper,we will extract the reliefs of three-dimensional model through the technology of the computer graphics.We use the mesh structure to handle the three-dimensional model.The three-dimensional model can be viewed as the linear combination of a base surface and relief parts.The unit normal vector of the base surface is estimated by using the adaptive Gaussian smoothing algorithm.Each vertex's height relative to the base surface is obtained by constructing differential equations between the adjacent mesh vertices,establishing the optimization equation by the least square method and using conjugate gradient descent method on the optimization equation.After the relative heights of each vertex are obtained,we use the Gaussian Mix Model to cluster these relative heights and make these heights into several sets.The vertexes in different sets respectively construct the base surface and the relief.At last,noise reduction will make the results better.Comparing with previous methods,this paper doesn't estimate the base surface directly but estimate the unit normal vector of the base surface and then calculate a large scale linear system to obtain the relative height of each vertex in the surface of the three-dimensional model.This algorithm is clear and easy to implement,and the method of estimating the unit normal vector of the base surface can be used in parallel computing,which greatly improves the efficiency.