[Registration] PCL-NDT codes calculate gauss_c1, c2 may have problem? equation 6.7

My confusion:

Paper: 2009 Phd Thesis <The Three-Dimensional Normal-Distributions Transform>

Equation here:

Code here:

   // Initializes the gaussian fitting parameters (eq. 6.8) [Magnusson 2009]
   const double gauss_c1 = 10.0 * (1 - outlier_ratio_);
   const double gauss_c2 = outlier_ratio_ / pow(resolution_, 3);

Question:
Why the PCL code write the constant c1, c2 as, pcl source code link:

Why the c1, c2 could be formulated as the codes said, and why 10 times on c1 also?

Other related issues to understand more:

1. https://github.com/PointCloudLibrary/pcl/issues/5056
2. same question in StackOverflow: https://stackoverflow.com/questions/75057084/normal-distributions-transform-pcl-ndt-codes-calculate-c1-c2-may-have-problem

Start with the gauss_c1 and gauss_c2 definitions in ndt.hpp and compare them with equation 6.7/6.8 in Magnusson's 2009 thesis. Review related issue #5056 and the linked discussion to determine whether the implementation is incorrect or the question reflects a notation difference. Done means establishing the intended formula and documenting or reporting a concrete correction if needed.