为了对等值面与子等值面进行提取和分组，在MC算法原理的基础上，提出了一种改进的等值面提取与子等值面分组算法。该算法首先将数据场分解为点、棱边、面与体元的拓扑结构；然后在整个数据场范围内求所有棱边与等值面的交点，并在面内连接交点形成面与等值面的交线，交线在体元内连接生成空间多边形；接着通过三角化各个体元内的空间多边形得到由顶点表与三角形表组成的等值面数据；最后根据三角形在顶点处的连接关系，采用种子算法对属于同一子等值面的三角形与顶点进行标记，属于同一子等值面的顶点与三角形将被存放在独立的顶点表与三角形表中。实验结果表明，该算法可以高效地实现等值面提取与子等值面的分组。

Based on the theory of Marching Cubes algorithm, an improved algorithm to extract isosurface from the 3D data field was introduced. At first the 3D data field was decomposed to the topological structure of points, lines, aces and cubes. Intersection points of the lines with the isosurface were calculated at first in the 3D data field. The intersection lines of the faces with the isosurface were gained by joining the intersection points in the faces. Intersection lines were joined together to form the space polygons in the cubes. The triangle mesh of the isosurface would be obtained by making triangle of the space polygons in each cube; The triangle mesh would be registered by a vertex table and a triangle table. Based on the relationship of connection among triangles at the vertexes, the seed algorithm was used to mark the vertexes and the triangles belong to the same child isosurface. And then vertexes and triangles belonging to the same child isosurface were registered by the individual vertex table and triangle table. It was proved by the instance that the algorithm could extract isosurface and group child isosurfaces with high efficiency.