Hi everyone, I am very confused the two commands, even though I see the help file. I would like to ask whether there is more about the explanation of these two commands and learning materials.
Hi, these commands allow you to trace principal curvature lines (etExtractCurvatureLines) and so-called conjugate lines (etExtractConjugateLines). Both are mostly useful to get an overview of how the connectivity of a quad mesh should look like if you want to achieve planar quads. If you want to read about those details I recommend to look into the following papers:
Geometric Modeling with Conical Meshes and Developable Surfaces
Freeform surfaces from single curved panels
http://www.geometrie.tuwien.ac.at/geom/ig/publications/oldpub/2008/panels08/panels.html
Designing Quad-dominant Meshes with Planar Faces.
http://www.evolute.at/technology-en/scientific-publications.html?id=64