Closing Meshes in Open3D: A Custom Approach

open3d, how to force the mesh to be closed. AttributeError: 'open3d.cpu.pybind.geometry.TriangleMesh' object has no attribute 'fill_holes'

As of my knowledge cutoff in October 2023, Open3D does not have a direct method like fill_holes to automatically close a mesh. However, you can use a combination of Open3D functions and additional logic to attempt to close the mesh. Here is a general approach to achieve this:

1. Identify Boundary Edges: Find the boundary edges of the mesh.
2. Create New Triangles: Create new triangles to fill the holes.

Here is a sample code to illustrate this process:

import open3d as o3d
import numpy as np

def close_mesh(mesh):
    # Step 1: Identify boundary edges
    edges = mesh.get_non_manifold_edges(allow_boundary_edges=True)
    boundary_edges = [edge for edge in edges if mesh.is_edge_boundary(edge)]
    
    # Step 2: Create new triangles to fill the holes
    for edge in boundary_edges:
        # Get the vertices of the boundary edge
        v1, v2 = edge
        
        # Find the neighboring vertices to form a triangle
        neighbors_v1 = mesh.get_vertex_neighbors(v1)
        neighbors_v2 = mesh.get_vertex_neighbors(v2)
        
        # Find a common neighbor to form a triangle
        common_neighbors = set(neighbors_v1).intersection(set(neighbors_v2))
        
        if common_neighbors:
            for v3 in common_neighbors:
                # Add the new triangle
                mesh.triangles.append([v1, v2, v3])
                mesh.triangle_normals.append([0, 0, 0])  # Placeholder normal

    # Remove duplicate triangles
    mesh.remove_duplicated_triangles()
    mesh.remove_duplicated_vertices()
    mesh.remove_degenerate_triangles()
    mesh.remove_non_manifold_edges()

    return mesh

# Load your mesh
mesh = o3d.io.read_triangle_mesh("path_to_your_mesh.ply")

# Close the mesh
closed_mesh = close_mesh(mesh)

# Save or visualize the closed mesh
o3d.io.write_triangle_mesh("closed_mesh.ply", closed_mesh)
o3d.visualization.draw_geometries([closed_mesh])

Explanation:

1. Identify Boundary Edges: The get_non_manifold_edges method is used to find edges that are not part of exactly two triangles. We then filter these to find boundary edges.
2. Create New Triangles: For each boundary edge, we find neighboring vertices and attempt to form new triangles to close the holes.
3. Clean Up: We remove duplicate and degenerate triangles and non-manifold edges to ensure the mesh is clean.

Note:

• This is a basic approach and may not work perfectly for all meshes, especially complex ones with large or irregular holes.
• You might need to refine the logic for finding common neighbors and forming triangles based on your specific mesh structure.
• For more advanced hole-filling techniques, consider using other libraries specialized in mesh processing, such as CGAL or MeshLab, and then import the processed mesh back into Open3D.

If Open3D has added new functionalities after my knowledge cutoff, please refer to the latest Open3D documentation for updated