Sorry if the title made you confused. I have googled a lot but none could help.
Suppose I have got a ply file, I can extract the vertices' positions, normals and colors. Also the face_vertices_index, i.e. the array is N by 3, each row forms a face (triangle), each value in the row is the index of the vertices.
So my question is how to get the postion/normal/color of the face. I know the loop will help solve this problem. But how to do it in a efficient way.
Suppose the number of vertices is bigger than 1e9 and the faces number is more.
Updated:
for example, to get the face postion:
face_vertices_index is some array like
array([array([0,1,2], dtype=int32), array([1,0,2], dtype=int32)], dtype=object)
this is the index of the vertices forming a triangle.
vertices = np.array([[-1.033,-0.794,0.262 ],[-1.038,-0.786,0.284],[-1.034,-0.786,0.272]]) Each vertices positions.
I could get face_posi a 1 by 3 array.
like face_posi[i] = np.mean(vertices[face_vertices_index[i]],axis=0)