如何在 Open3D 中裁剪/分割网格

Question

Is it possible to split the mesh in Open3D based on vertex threshold?

For example, I need the mesh into two stl outputs, one with the z-vertex less than some value (with x and y throughout the domain) and second stl with remaining z-vertex.

In Open3D documentation, there is a way to crop the mesh. But it is according to the triangles assigned. Below is the code from the website itself.

mesh1 = copy.deepcopy(mesh)
mesh1.triangles = o3d.utility.Vector3iVector(
np.asarray(mesh1.triangles)[:len(mesh1.triangles) // 2, :])
mesh1.triangle_normals = o3d.utility.Vector3dVector(
np.asarray(mesh1.triangle_normals)[:len(mesh1.triangle_normals) // 2, :])

o3d.visualization.draw_geometries([mesh1])

So, based on this, How can I crop/split the mesh with respect to vertex? I can access the vertex with mesh.vertices.

Any leads will be appreciated.

Regards, Sunag R A.

Answer 1

I'm not familiar with Open3D, but as there is points and facets arrays, you can simply do a loop like this:

points = [...] # from your mesh
faces = [...] # from your mesh

threshold = 0  # z threshold
# the crop parts
below = []
above = []
for face in faces:
    if all(points[p][2] < threshold   for p in face):
         below.append(face)
    else:
         above.append(face)

It looks every face of the mesh, when all face points are below the threshold the face is put in list below , else in above