stereoRectify, projectPoints, triangulatePoints

edit

Hi, I am simulating 3D->2D->3D process. first, i project worldPoint to two camera points(left and right) then, use stereoRectify caculates the P1, and P2 finally use P1, P2 and two camera points to caculate the worldPointEst again.

If the the rvecL is 0 degree in all direction, WorldPoint=WorldPointEst

However, if i add any degree in x or y direction, WorldPoint != WorldPointEst (surpposed to be the same)

Any help for this? Thanks in advanced

----------------------------------------code sample---------------------------------------------------

projectPoints(worldPoint, rvecL, tvecL, cameraMatrix_L, distCoeffs_L, imagePoint_L);
projectPoints(worldPoint, rvecR, tvecR, cameraMatrix_R, distCoeffs_R, imagePoint_R);

stereoRectify(cameraMatrix_L, distCoeffs_L, cameraMatrix_R, distCoeffs_R, cv::Size(640,480), R_rotation_Matrix_rev, R_translation, R1, R2, P1, P2, Q);

for(int i =0; i<imagePoint_L.size(); i++)
{
triangulatePoints(P1, P2, Mat(imagePoint_L[i]), Mat(imagePoint_R[i]), worldPointEst);
}