细节保持的曲面浅浮雕算法

为保持曲面浮雕的细节特征,改善浮雕与背景曲面的过渡效果,提出一种细节保持的曲面浮雕算法.首先采用Canny算子在梯度域定位内外轮廓,获得连续的梯度域;其次提出非线性函数,并用其压缩梯度幅值实现形状压缩;再通过双边滤波算子来保持和增强浮雕细节;最终通过求解积分方程重建曲面浮雕.该算法将背景曲面作为积分方程的优化条件,使浮雕在轮廓处向曲面光滑过渡;在重建过程中利用Fourier变换的微分性质在频域实现方程的精确求解,无需设置迭代收敛条件;通过调整参数可方便地控制浮雕整体变化范围、细节锐化程度以及浮雕与背景曲面的过渡效果.实验结果表明,文中算法参数的几何意义直观,所得曲面浮雕细节清晰,边界过渡自然.

Detail-Preserving Bas-relief on Surface from 3D Scene

A novel algorithm for making the bas-relief from 3D shape onto a curved surface is proposed in order to preserve relief details and get smooth relief-background transitions.Firstly,a continuous gradient field is obtained by special treatment on the silhouettes,which are located by Canny operator.Secondly,a flattened shape is achieved by compressing the magnitude of the gradient using a proposed non-linear function.Subsequently,the details on the original 3D shape are maintained and also enhanced using the bilateral filtering on the gradient domain.Finally,the bas-relief on curved surface is reconstructed from the gradient domain by solving an integral equation.In order to eliminate the steps between relief and background,the background surface is associated to the equation as an optimal condition.The equation is solved accurately in frequency field with no need to set iteration stopping criteria by taking advantages of differential properties of Fourier transformation.The height of bas-relief,the detail sharpness and the transition smoothness can be effectively controlled by tuning the parameters.The experiments demonstrate that the parameters in the algorithm have intuitive geometry meaning,and the obtained bas-relief owns distinct details and smooth relief-background transitions.