Normal projection vectors: meshmath.exe vs. Model-to-Model Distance

Hello Slicer(SALT) devs,

I am revising a python script to run the Model-to-Model Distance module in CLI so I can automate the process for a large batch of VTKs. Specifically, I’m looking to extract the normal projections of the distance vectors (between correspondent points) and use them for statistical testing.

I know that there is the “MagNormVector” field in the output VTK after running the module, and I also know that the hidden “MeshMath.exe” application (included in SlicerSALT’s /bin/ folder but has mostly been integrated into Model-to-Model Distance) includes a “magNormDir” argument to get the magnitude of the normal projections.

I’m aware that “MagNormVector” is 3D data and “magNormDir” is 1D, but are these functionally the same in terms of the vectors being calculated? I just want to make sure the vector math is equivalent before I commit to scripting one method over the other (especially since MeshMath is much easier to work with in CLI).

Thanks in advance!