Hi, I am new to OpenMesha and currently working with the python bindings to build a quick prototype of my code before moving to c++. attached a simple icosahedron structure. I defined 12 vertices and 20 faces. When using the vf circulator I experience that not all neighbouring face of a vertex are found. I also found that the number of faces is sensitive to the order of the vertex handles when defining a face. when looking at the indices some are set to -1. Is this expected behavior or am I missing something fundamental? Please find the minimal example below. Any help or comments would be greatly appreciated! Best regards, Marc Siggel import OpenMesh as om import numpy as np mesh = om.TriMesh() mesh_notebook = {} face_notebook = {} radius = 3.0/4.0/np.pi phi = 0.5*(1+np.sqrt(5)) a = radius / np.sqrt(phi*np.sqrt(5)) mesh_notebook[0,"handle"] = mesh.add_vertex([a*phi,0,a]) mesh_notebook[1,"handle"] = mesh.add_vertex([a*phi,0,-a]) mesh_notebook[2,"handle"] = mesh.add_vertex([-a*phi,0,-a]) mesh_notebook[3,"handle"] = mesh.add_vertex([-a*phi,0,a]) mesh_notebook[4,"handle"] = mesh.add_vertex([a,a*phi,0]) mesh_notebook[5,"handle"] = mesh.add_vertex([-a,a*phi,0]) mesh_notebook[6,"handle"] = mesh.add_vertex([-a,-a*phi,0]) mesh_notebook[7,"handle"] = mesh.add_vertex([a,-a*phi,0]) mesh_notebook[8,"handle"] = mesh.add_vertex([0,a,a*phi]) mesh_notebook[9,"handle"] = mesh.add_vertex([0,-a,a*phi]) mesh_notebook[10,"handle"] = mesh.add_vertex([0,-a,-a*phi]) mesh_notebook[11,"handle"] = mesh.add_vertex([0,a,-a*phi]) face_notebook[0,"handle"] = mesh.add_face(mesh_notebook[7,"handle"], mesh_notebook[0,"handle"], mesh_notebook[9,"handle"]) face_notebook[1,"handle"] = mesh.add_face(mesh_notebook[9,"handle"], mesh_notebook[7,"handle"], mesh_notebook[6,"handle"]) face_notebook[2,"handle"] = mesh.add_face(mesh_notebook[9,"handle"], mesh_notebook[6,"handle"], mesh_notebook[3,"handle"]) face_notebook[3,"handle"] = mesh.add_face(mesh_notebook[7,"handle"], mesh_notebook[1,"handle"], mesh_notebook[10,"handle"]) face_notebook[4,"handle"] = mesh.add_face(mesh_notebook[7,"handle"], mesh_notebook[10,"handle"], mesh_notebook[6,"handle"]) face_notebook[5,"handle"] = mesh.add_face(mesh_notebook[10,"handle"], mesh_notebook[6,"handle"], mesh_notebook[2,"handle"]) face_notebook[6,"handle"] = mesh.add_face(mesh_notebook[0,"handle"], mesh_notebook[1,"handle"], mesh_notebook[7,"handle"]) face_notebook[7,"handle"] = mesh.add_face(mesh_notebook[6,"handle"], mesh_notebook[3,"handle"], mesh_notebook[2,"handle"]) face_notebook[8,"handle"] = mesh.add_face(mesh_notebook[0,"handle"], mesh_notebook[4,"handle"], mesh_notebook[8,"handle"]) face_notebook[9,"handle"] = mesh.add_face(mesh_notebook[8,"handle"], mesh_notebook[4,"handle"], mesh_notebook[5,"handle"]) face_notebook[10,"handle"] = mesh.add_face(mesh_notebook[8,"handle"], mesh_notebook[3,"handle"], mesh_notebook[5,"handle"]) face_notebook[11,"handle"] = mesh.add_face(mesh_notebook[1,"handle"], mesh_notebook[4,"handle"], mesh_notebook[11,"handle"]) face_notebook[12,"handle"] = mesh.add_face(mesh_notebook[4,"handle"], mesh_notebook[5,"handle"], mesh_notebook[11,"handle"]) face_notebook[13,"handle"] = mesh.add_face(mesh_notebook[5,"handle"], mesh_notebook[11,"handle"], mesh_notebook[2,"handle"]) face_notebook[14,"handle"] = mesh.add_face(mesh_notebook[0,"handle"], mesh_notebook[1,"handle"], mesh_notebook[4,"handle"]) face_notebook[15,"handle"] = mesh.add_face(mesh_notebook[3,"handle"], mesh_notebook[2,"handle"], mesh_notebook[5,"handle"]) face_notebook[16,"handle"] = mesh.add_face(mesh_notebook[0,"handle"], mesh_notebook[8,"handle"], mesh_notebook[9,"handle"]) face_notebook[17,"handle"] = mesh.add_face(mesh_notebook[9,"handle"], mesh_notebook[8,"handle"], mesh_notebook[3,"handle"]) face_notebook[18,"handle"] = mesh.add_face(mesh_notebook[1,"handle"], mesh_notebook[10,"handle"], mesh_notebook[11,"handle"]) face_notebook[19,"handle"] = mesh.add_face(mesh_notebook[2,"handle"], mesh_notebook[10,"handle"], mesh_notebook[11,"handle"]) print(len(mesh.faces())) # should be 20 for edge in mesh.vf(mesh_notebook[0,"handle"]): print(edge.idx()) # should be 5 for j,i in face_notebook: print(face_notebook[j,i].idx()) # some are defined as -1 - default behavior?