在使用OpenCV的三维立体重建的库时，一个重要的步骤就是生成左右视图的差异图Disparity，而控制生成disparity的参数的类是cv::StereoBM，我们有时候需要拷贝一份cv::StereoBM，然后改变其中的参数值，但是如果用默认的等号‘=’来进行拷贝，其实是浅拷贝，如果改变拷贝项的参数值，原来的参数值也会跟着改变，所以我们需要自己写一个深拷贝的函数，如下所示：

 

/** * Deep copy cv::StereoBM bm1 to bm2 */void copy_bm(const cv::StereoBM &bm1, cv::StereoBM &bm2) {    if (!bm1.state) {        return;    }    bm2.init(CV_STEREO_BM_NORMALIZED_RESPONSE, 0, 21);    bm2.state->preFilterSize = bm1.state->preFilterSize;    bm2.state->preFilterCap = bm1.state->preFilterCap;    bm2.state->SADWindowSize = bm1.state->SADWindowSize;    bm2.state->minDisparity = bm1.state->minDisparity;    bm2.state->numberOfDisparities = bm1.state->numberOfDisparities;    bm2.state->textureThreshold = bm1.state->textureThreshold;    bm2.state->uniquenessRatio = bm1.state->uniquenessRatio;    bm2.state->speckleWindowSize = bm1.state->speckleWindowSize;    bm2.state->speckleRange = bm1.state->speckleRange;}