Hi Michael,

Here are two example files. In the first file, you will see a cleaner result obtained by extracting the generated section plane.

I also did another experiment in file #2 where I compared the "Section plane edges extraction," "projecting a straight line," and "intersecting a surface" methods on normal and analytical surfaces. I found that the Curves/Isect command produces the best and cleanest results.
I'm not sure if using analytical surfaces actually makes a difference. In example 1, the curves generated from analytical surfaces have fewer points, but in example 2, the opposite is true.