I am triangulating 3D points using OpenCV triangulation function for monocular sequence that sometimes works fine but I have noticed when two camera poses are close to each other then the triangulated points are far away. I can understand the issue that is since the camera poses are close then the ray intersection from two cameras is being take place far away from the camera. That is why it creates the 3D points far away. I have also noticed that the distance requirement between two cameras for correct triangulation varies in different cases.Currently I am trying to find parallax between two pose and if that is above a certain threshold(I have chosen 27) then proceed to triangulate but I does not look correct for all the cases.

My code for calculating parallax as following-

float checkAvgParallex(SE3& prevPose, SE3& currPose, std::vector<Point2f>& prevPoints, std::vector<Point2f>& currPoints, Mat& K) {
    Eigen::Matrix3d relRot = Eigen::Matrix3d::Identity();
    Eigen::Matrix3d prevRot = prevPose.rotationMatrix();
    Eigen::Matrix3d currRot = currPose.rotationMatrix();
    relRot = prevRot * currRot;
    float avg_parallax = 0.;
    int nbparallax = 0;

    std::set<float> set_parallax;

    bearingVectors_t prevBVs;
    bearingVectors_t currBVs;

    points2bearings(prevPoints, K, prevBVs);
    points2bearings(currPoints, K, currBVs);

    for (int i = 0; i < prevPoints.size(); i++) {
        Point2f unpx = projectCamToImage(relRot * currBVs[i], K);
        float parallax = cv::norm(unpx - prevPoints[i]);
        avg_parallax += parallax;
        nbparallax++;
        set_parallax.insert(parallax);
    }
    if (nbparallax == 0)
        return 0.0;
    avg_parallax /= nbparallax;

    auto it = set_parallax.begin();
    std::advance(it, set_parallax.size() / 2);
    avg_parallax = *it;

    return avg_parallax;
}

And sometime when parallax between camera does not exceed 27 so, triangulation won't work, due to this my further pose calculation in SLAM system stops due to lack of 3D points.

So can anyone suggest me alternative strategy using which I can estimate correct 3D points and my SLAM system wont suffer due to lack of 3D points, please?