How can I align a normal vector to the camera?

[AshengLin]

Excuse me.
I have a mesh object, and there's a important face I would like to observe.
I need to rotate the meshes so that the surface I am interested in is facing the camera.
So, right now I have all vertices, faces, the important face center, and the face normals, can I align the face normals to camera?

I can rotate the mesh by degree or matrix, but I don't know the initial camera view point degree.
I have been stuck on this question for a week.

ps: I'm using open3d, trimesh with python.