I try to determine curvature of the surface. How use Ev1Der or Ev2Der I can do it?
to use Ev1Der you have to apply the correct u and v parameters and you get the according tangent vector in u and v direction. Same with Ev2Der you get the second derivative.
What’s exactly your problem?
Here is an SDK sample that might help you.
You can find more SDK samples in our developer samples repo on GitHub.