说明：  opencv中自带的sgbm算法（半全局匹配）的源代码，具有很好的立体匹配效果，是opencv中自带算法中速度和效果较好的一种。
(Sgbm algorithm with OpenCV (semi global matching) of the source code, has the very good effect of stereo matching, opencv comes with the speed and the effect of a good algorithm.)