Function findNormal

pdal/private/MathUtils.cpp:484–523

}

NormalResult findNormal(const PointView& view, PointIdList neighbors)
{
    using namespace Eigen;

    NormalResult result;
    if (neighbors.size() < 3)
    {
        result.msg = "Not enough neighbors to compute normal.";
        return result;
    }

    // Check if the covariance matrix is all zeros
    auto B = math::computeCovariance(view, neighbors);
    if (B.isZero())
    {
        result.msg = "Covariance matrix is all zeros. This suggests a large "
            "number of redundant points.";
        return result;
    }

    SelfAdjointEigenSolver<Matrix3d> solver(B);
    if (solver.info() != Success)
    {
        result.msg = "Cannot perform eigen decomposition during normal calculation.";
        return result;
    }

    // The curvature is computed as the ratio of the first (smallest)
    // eigenvalue to the sum of all eigenvalues.
    auto eval = solver.eigenvalues();
    double sum = eval[0] + eval[1] + eval[2];

    result.curvature = sum ? std::fabs(eval[0] / sum) : 0;

    // The normal is defined by the eigenvector corresponding to the
    // smallest eigenvalue.
    result.normal = solver.eigenvectors().col(0);

    return result;
}

NormalResult findNormal(double x, double y, double z, PointView& v, double radius)
{