A series of vertical parallel lines dissect the layered model to form a special grid, where the crosspoints made by each interface and all parallel lines are the knots which can approximately represent the interface. 模型划分是用一系列的垂直平行线(VPL)划分所研究的模型,平行线与各层界面相交构成对模型的一种特殊剖分,一系列的交点则为近似表示模型界面的节点。