四叉树

说明：  自顶向下(top-down)的分割方法:按常规四叉树的方法进行，直接生成M码 ? 从底向上(down-top)的合并方法： – 首先按M码的升序排列方式依次检查四个相邻M码对应的属性值 ? 如果相同，合并为一个大块 ? 否则，储四个格网的参数值（M码、深度、属性值） – 第一轮合并完成后，依次检查四个大块的值（此时， 仅需检查每个大块中的第一个值） ? 若其中有一个值不同或某子块已存储 ? 则不作合并而记盘 – 通过上述方法，到没有能够合并的子块为止
(The top-down (top-down) segmentation method: according to the conventional method of four binary tree, M code generation directly from the bottom up - (down-top) - the combination method: firstly according to the M code of the ascending way in order to check the corresponding properties of four adjacent M code value, if the same, merged into a large, otherwise four grid storage, parameter values (M code, depth, attribute value) - the first round after the completion of the merger, in order to check four large value (at this time, Just check the first value in each block. if one of the values is different or a block has been stored, then the record is not merged - by the method mentioned above, until the block is not merged)