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Fill Up Holes

In one sentence: Automatically detect and fill all open boundary loops (holes) in the mesh with new triangles.

Overview

Workbench: Mesh
Menu: Mesh → Meshes → Fill-up Holes…
Command: Mesh_FillupHoles
Shortcut: none

Automatically detects all open boundary loops in the mesh and fills them with new triangles. A size filter lets you skip intentionally open boundaries (e.g., the open base of a vase) by limiting fills to holes with fewer than N boundary edges.

Intuition

After importing a scan mesh, there are often small holes from scan occlusions or defects. Fill Up Holes closes all of them at once. For a mesh to be 3-D printable (watertight) all holes must be closed — this tool does that automatically.

For more control over which specific holes to fill, use Fill Hole Interactively.

When to use it

  • After importing a scan mesh with multiple small holes.
  • After Evaluate and Repair reports open boundaries.
  • As part of a batch repair workflow: Import → Evaluate & Repair → Fill Holes → Evaluate Solid → Export.

Step-by-step

  1. Select the mesh.
  2. Choose Mesh → Meshes → Fill-up Holes….
  3. Set Max hole size (number of boundary edges).
  4. Click OK. All holes with ≤ that many boundary edges are filled.
  5. Run Evaluate Solid to confirm the mesh is now closed.

Parameters

Parameter Description
Max hole size Fill only holes with fewer than this many boundary edges. Set high (e.g. 1000) to fill all holes.

Common mistakes and pitfalls

The fill algorithm is flat (fan triangulation)

FreeCAD uses a simple fan triangulation to fill holes: a centre point plus triangles to each boundary edge. This produces a flat or slightly concave patch regardless of surrounding curvature. For curved surfaces, inspect and manually refine large filled areas.

Large holes may be intentional

A vase model has an intentionally open base. Setting Max hole size too high will fill it. Use Fill Hole Interactively for selective filling.

Python API

import FreeCAD as App

mesh_obj = App.ActiveDocument.getObject("Mesh")
mesh = mesh_obj.Mesh.copy()
mesh.fillupHoles(10)   # fill holes with up to 10 boundary edges
mesh_obj.Mesh = mesh
App.ActiveDocument.recompute()

See also