Repairing Holes, Floaters and Broken Pieces in AI Meshes

What goes wrong in AI meshes

StraySpark, which sells a cleanup add-on, says “a generator is optimising for what the model looks like from outside, not for whether the surface is one closed skin,” giving plates that overlap instead of joining, seams that almost meet and pieces that float a hair apart. It is a vendor’s description, not a measured rate. The defect types to look for, and what each does downstream:

• Floaters: small disconnected pieces. They add triangles, and StraySpark says “hundreds of open shells” is the opposite of the closed surface QuadriFlow wants (QuadriFlow rejected both of its Meshy test files).
• Fragmented shells: one object made of many separate pieces. StraySpark reports one Meshy file with 633 separate shells and 35,842 open border edges. That is one file, not a rate.
• Near-miss seams: vertices that almost touch but are not joined, so the surface is open.
• Holes: missing faces.
• Inner faces: geometry sealed inside the shape.
• Flipped normals: faces that shade as if inside out.

One figure with useful context comes from a Tech-Artists.Org forum thread (August 2026, posted by the author of a public mesh-QA benchmark, not independently checked). The poster reports non-manifold edges on 33 of 101 TripoSG models and 14 of 97 TripoSR models, then adds that the median affected model carried only four such edges, and that TripoSG’s median mesh has about 1.37 million faces. That second number changes how you read the first. The presence of a defect and the amount of work it causes are different questions.

Defect frequency by generator has not been measured here. Checking raw AI 3D output shows how to take those counts on your own files.

Diagnose before you touch anything

Each defect has a Blender tool that finds it, and most are selection operators, so you can see the problem before deciding what to do about it.

Read the Non Manifold result with its options in mind. Wire, Boundaries, Multiple Faces, Non Contiguous and Vertices are separate options, so you can look at open holes alone.

Procedure

Work on a duplicate. Keep the untouched original for baking later. The Clean up operators work on what is selected, so select all (A) in Edit Mode first unless you mean to limit them.

1. Inspect first. Import the file (importing AI 3D models into Blender), run the checks above and orbit the model in solid view. Why: you want to know whether you have a few holes or a shattered mesh before choosing a fix.
2. Delete Loose. In Edit Mode: Mesh > Clean up > Delete Loose. The manual describes it as deleting the selected vertices, edges and optionally faces that are not connected to anything. Why: it clears stray vertices and edges the generator leaves behind.
3. Remove floating pieces. Delete Loose targets geometry connected to nothing, so separate shells made of real faces will usually still be there. Hover over the main body and press L (Select Linked), or click it and press Ctrl-L, then invert with Ctrl-I and delete what remains. Check first that nothing you want is in that selection. If you would rather sort the pieces, Mesh > Separate > By Loose Parts (P) makes an object of every disconnected piece, which is often easier to review. Alternatively, the Remesh modifier has a Remove Disconnected option with a Threshold; the manual describes it as filtering small disconnected pieces out of the modifier’s output, and says thin parts of the input can become loose bits.
4. Merge by Distance. Mesh > Clean up > Merge by Distance merges selected vertices closer together than Merge Distance. Start with a small value and increase gradually, since a large one will merge real detail. Meshy’s help article notes a default of 0.0001 m and suggests trying about 0.001 m if that is too small. Options include Unselected and Sharp Edges. Why: it can join near-miss seams.
5. Recalculate normals. Mesh > Normals > Recalculate Outside (Shift-N). The manual notes the mesh does not need to be a closed volume. Confirm with Face Orientation afterward. Mesh > Normals > Flip handles individual faces.
6. Fill Holes. Mesh > Clean up > Fill Holes fills each hole in the selection with a face; Sides caps how many edges a hole may have (0 fills all). A small Sides value limits filling to small holes; large gaps filled this way are invented geometry. For a large opening, the manual points to Face Fill or Grid Fill (Face > Grid Fill), which needs a roughly rectangular loop of edges.
7. Optional tidy-ups in the same Clean up menu: Degenerate Dissolve (collapses edges shorter than Merge Distance), Limited Dissolve, Split Non-Planar Faces, Split Concave Faces. Use only if a later step complains.
8. If the shell is still broken, voxel remesh. In Sculpt Mode, Tool Settings > Remesh, set Voxel Size, press Voxel Remesh (Ctrl-R). The Remesh modifier page describes voxel output as a new manifold mesh built to preserve the original volume, and the remeshing page says the result has no inner self-intersecting geometry. StraySpark adds that overlapping plates, near-miss seams and open shells end up inside a single closed volume, so the output is “closed and manifold by construction”. It removes all mesh data layers from the original, so rebuild UVs (UV and texture fixes) and rebake from the original. Full procedure: retopology in Blender for AI meshes.

If the input is a thin sheet with no thickness, voxel remeshing has nothing to work with. The Remesh modifier page says the input should have some thickness and suggests a Solidify modifier above Remesh for completely flat parts. Meshy’s help article warns that Solidify can create self-intersections on complex models, so re-check afterward.

When a repair makes things worse

A fill that closes a hole is not automatically an improvement. In that same forum thread, the poster describes a repair tool whose hole-fill reverted itself because it would have introduced 336 non-manifold edges. The mesh came out watertight anyway, because all of its 25 open boundary edges were on floating debris that got deleted. Another participant, working on skinned meshes, says their engine does not allow non-manifold geometry on those at all while static mesh artists get away with more, and that their QA tools only auto-fix the “most bullet proof” issues.

Two practical points follow. Decide how strict to be by what the asset does, since a character and a background rock do not need the same standard. And check your result after each automatic fix rather than trusting that a closed mesh was closed the way you intended.

When voxel remesh is the wrong answer

If the mesh will be rigged and deformed, or if thin parts (fingers, straps, antennae) matter, voxel remeshing can fuse or drop them: StraySpark says a voxel grid cannot represent anything thinner than one voxel. In those cases repair by hand, or regenerate the asset. Method choice sits on retopology for AI 3D models.

When to give up and regenerate

A Tripo cleanup guide, from a vendor with its own mesh product to sell, was noted as advising regeneration over repair for a badly tangled model; we could not re-open that page at our final check, so treat that as unconfirmed. The mechanics support weighing it anyway: a mesh needing a full remesh loses its UVs either way, so the old surface is only worth keeping if its shape is right. How to weigh that against credits and your own hours is on cleanup time per asset.

When to stop

Stop when there are no visible holes or stray pieces from the angles the player will see, the model is one object or an intended set of objects, and later steps (remesh, bake, import) run without errors. Full watertightness is a printing goal. On a game prop, chase it only if a later step or your engine demands it, as QuadriFlow and the skinned-mesh rule in the forum report above do. Do not infer print-readiness from a clean game repair.

Not verified

Defect rates per generator, and Blender 4.5 LTS menu wording. The 3D Print Toolbox (listed on Blender’s Extensions site) offers geometry checks and Make Manifold, and Meshy’s help article says it may not fully fix complex AI-generated meshes; its current panel names were not confirmed from an official page and it is covered under printing.

This page is part of the Cleaning Up AI 3D Models section.