使用背景建模法和时间差分法的前景分割，使用找轮廓的方式显示移动物体的位置-Background modeling using time-difference method and the prospect of partition, use the display profile to find the position of moving objects

交错网格---非均匀介质二维声波方程(一阶压力--速度)、2阶时间差分、2阶空间差分精度-Staggered grid--- dimensional inhomogeneous medium acoustic wave equation (first-order pressure- speed), second-order time differential, second-order spatial difference accuracy