如何获得良好的坐标与triangulatePoints()从openCV

左边有一个点，x:1168px, y:1140px右边有一个点，x:1062px, y:1167px。我用我的程序得到的真实坐标是:120.91,4.94059，-175.609 (x, y和z以mm为单位)。X和Y似乎是正确的，但Z不是，点离我的相机大约1米远。

现在我有这样的代码:

FileStorage fsI("intrinsics.yml", FileStorage::READ);
Mat matI1, matI2, matD1, matD2;
fsI["M1"] >> matI1;
fsI["M2"] >> matI2;
fsI["D1"] >> matD1;
fsI["D2"] >> matD2;
CvMat camInt1 = matI1, camInt2 = matI2, camDist1 = matD1, camDist2 = matD2;
FileStorage fs("extrinsics.yml", FileStorage::READ);
Mat mat1, mat2;
fs["P1"] >> mat1;
fs["P2"] >> mat2;
CvMat projMat1 = mat1, projMat2 = mat2;
double pointImg1_a[2] = { 1168, 1140};
Mat pointImg1 = Mat(2,1, CV_64FC1, pointImg1_a);
CvMat _pointImg1 = cvMat(1,1,CV_64FC2,pointImg1_a);
double pointImg2_a[2] = { 1062, 1167};
Mat pointImg2 = Mat(2,1, CV_64FC1, pointImg2_a);
CvMat _pointImg2 = cvMat(1,1,CV_64FC2,pointImg1_a);
cvUndistortPoints(&_pointImg1,&_pointImg1,&camInt1,&camDist1);
cvUndistortPoints(&_pointImg2,&_pointImg2,&camInt2,&camDist2);
Mat point4D = Mat(4,1, CV_64FC1);
cv::triangulatePoints(mat1, mat2, pointImg1, pointImg2, point4D);   
double w = point4D.at<double>(3,0);
double x = point4D.at<double>(0,0)/w;
double y = point4D.at<double>(1,0)/w;
double z = point4D.at<double>(2,0)/w;
cout << x << ", " << y << ", " << z << endl;
return 0;

我尝试不使用cvUndistortPoints()和其他坐标，结果有时是正确的，但并不总是。我真的不知道这个错误是从哪里来的。(我也是新的openCV)谢谢你的帮助。