What is nx, ny and nz values for each point in content of the scene_dense.ply

[dinushazoomi]

Hi all, I am new to OpenMVS, when I read the header of scene_dense.ply it shows a set of values with nx, ny, and nz, I wonder what they represent.

Any help would be highly appreciated
Thank you

[cdcseacave]

normal of each point

[dinushazoomi]

Sorry for my lack of knowledge on this, can you bit more explain the normal.