What is the normal vector in the obj file?

Question

Blender

There is a vn parameter in the obj format file, where it comes from, I understand that this is a normal vector, but I don’t know exactly how it is calculated and to which plane, who came across obj format files, tell me, I don’t know what to do already and manually recalculated and English-language forums reshuffled, but did not understand, it is not clearly written anywhere.

Answer 1

Vn is usually considered as a normalized vector product of vectors built on the vertices of a triangle (face). Those. usually how many triangles are in the mesh, only the normals.