基于三维网格单元的等值面梯度抽取法

针对三维网格等值面抽取中存在的二义性问题,提出三维网格单元等值面梯度抽取法.本算法利用梯度在三维网格单元外表面计算等值点,勾勒等值面轮廓,而后以添加网格内等值点方式明确等值面在网格内部凹凸方向,提出映射后Delaunay三角面片提取法,在二维空间完成等值面抽取.为减少计算及绘制所需存储空间,采用调整步长及合并阈值的方法控制输出三角面片数量.实验结果证明,该算法可一次性抽取等值面准确轮廓,克服了Marching Cubes算法的二义性,生成面片可真实描述三维网格内部等值面走势,通过调整参数保证了等值面精度,降低了存储代价.

3D Mesh Based Isosurface Gradient Extraction Algorithm

In order to avoid the ambiguity of isosurface extraction process in 3D mesh, an isosurface extraction algorithm based on gradient in 3D data space was proposed. In this method, contour points were calculated on the surface of the voxel based on gradient step by step. The outline of the isosurface was drew to make sure that the isosurface was concave or convex by adding contour points inside the voxel. The map-Delaunay method was proposed to get triangles of the isosurface in 2D. The step and merge-threshold were used to control the quantity of triangles to decrease the cost of storage. The experiment results showed that with this algorithm, the accurate contour was extracted just for once and the shortcomings of Marching Cubes algorithm was overcome. The isosurface in the voxel could be extracted exactly. The accuracy of the isosurface was ensured, and the cost of storage was reduced by changing the parameters.