Scan Cleaner - 3d scan fixer

you will find this add-on in the modifiers tab as you would with the modifiers place them in execution order top to bottem.
then hit run it may take a while to execute so be pacient.

there are some presets to get you started i prefer the Full scan to Quad Asset

• Apply Transforms — bakes in rotation and scale first, so the later remesh measures sizes correctly and the bake aligns properly.
• Merge by Distance (0.00005) — welds the near-duplicate verts scanners produce, with a fine threshold so real detail is kept.
• Delete Loose — removes stray verts/edges/faces (floating scanner noise).
• Degenerate Dissolve — collapses zero-area faces and zero-length edges that would otherwise break remesh/bake.
• Remove Small Islands (keep largest) — throws away every disconnected chunk except the main body, killing background blobs.
• Make Watertight — fills open boundary holes so the surface is closed (this also helps QuadriFlow succeed).
• Recalculate Normals — flips everything to face consistently outward.
• Retopo + Bake (QuadriFlow, ~5k faces) — rebuilds clean quad topology at ~5,000 faces, auto-UVs it, and bakes Diffuse, Normal, AO, Roughness and Metallic from the original scan onto the new low-poly. The original is hidden; the finished _retopo mesh is left selected.