请教opencv2.4.4函数initUndistortRectifyMap的有关问题

stereoRectify(cameraMatrix_l,distCoeffs_l,cameraMatrix_r,distCoeffs_r,Im_src.size(),rotation,translation,R1,R2,P1,P2,Q,CV_CALIB_ZERO_DISPARITY,1);
        Mat mX1,mX2,mY1,mY2;
        initUndistortRectifyMap(cameraMatrix_l,distCoeffs_l,R1,P1,Im_src.size(),CV_32FC1,mX1,mY1);        //        计算无畸变的校正映射
        initUndistortRectifyMap(cameraMatrix_r,distCoeffs_r,R2,P2,Im_src.size(),CV_32FC1,mX2,mY2);
        Mat Imgl_ste,Imgr_ste;
        remap(Imgsrc_l[0],Imgl_ste,mX1,mY1,INTER_LINEAR);
        remap(Imgsrc_r[0],Imgr_ste,mX2,mY2,INTER_LINEAR);