In this paper , a gray video md - 3d - spiht algorithm is proposed , which extends the md - spiht algorithm into 3d - spiht . this method is to divide the 3 - d wavelet coefficients into some number p of different groups according to their spatial and temporal relationships , and then to encode each group independently using 3d - spiht algorithm , so that p independent embedded 3d - spiht substreams are created . multiple descriptions are created 2 、将md - spiht方法推广应用于视频序列,提出了灰度视频md - 3d - spiht算法,该算法先对一组视频图象进行多级离散三维小波变换,在小波域建立空间方向树,及对空间方向树分组,再分别对各组进行3d - spiht编码,即产生多个描述,且每一描述的码流是完全嵌入式的,易于实现质量可分级编码。
It ' s the process of mapping the temporal conceptual model to the relational data model that we transform the four dimension temporal relationship into the two dimension snapshot relationship , and model the component and the time - varying relationship and attribute in the system 在将一个时态的概念模型映射至关系的数据模型的过程中,我们首先将一个四维的时态关系转化为一个二维的快照关系(即如何表达时间) ,再将sidss时态关系数据库的组件及随时间变化的关系和随时间变化的属性模型化。