🎯 Lesson: Mesh Cleanup

🧠 Focus: Learn how to clean up and optimize scanned 3D models by repairing geometry, reducing noise, and preparing them for modeling or printing.

✅ Lesson Summary

After completing a 3D scan, the resulting mesh is rarely perfect. It often includes noise, holes, overlapping geometry, or unnecessary complexity. Mesh cleanup is the essential post-scan step that transforms raw scan data into usable 3D models. This lesson introduces key tools and techniques used to polish and refine your scanned models.

🎓 Learning Objectives

By the end of this lesson, students will be able to:

• Understand common mesh issues in raw 3D scan data

• Use basic mesh editing tools to clean, fill, and repair 3D models

• Optimize mesh quality for 3D printing, modeling, or simulation

• Use free and professional mesh editing software effectively

• Export finalized meshes in usable formats

📘 Lesson Content

🟩 1. What Is a Mesh?

A mesh is the 3D surface of your scanned object, made up of vertices, edges, and faces (typically triangles).
Scanned meshes are usually stored in formats like .STL, .OBJ, or .PLY.

Common mesh issues:

• Holes: Gaps in the surface caused by missing data

• Non-manifold geometry: Faces or edges that confuse slicers or 3D editors

• Noise: Unwanted bumps or spikes

• Overlapping geometry: Double surfaces or intersecting faces

• Too many polygons: Overly complex mesh, hard to edit or print

🟨 2. Basic Mesh Cleanup Workflow

1. Import scan data into mesh editing software

2. Isolate and delete floating or stray mesh fragments

3. Repair holes using auto-fill or manual patching

4. Remove noise with smooth/relax filters

5. Simplify (decimate) mesh if needed

6. Check for watertightness for 3D printing

🟥 3. Mesh Editing Tools and Software

🟦 4. Hole Filling and Repairing

• Automatic fill: Most tools offer “Close holes” or “Fill all” functions

• Manual patching: Use vertex/edge tools for more control

• Bridge tool: Fill a gap by connecting two edges

• Watertight check: Ensures model is fully enclosed (important for printing)

🔧 MeshLab: Use Filters > Remeshing, Simplification > Close Holes

🟧 5. Noise Reduction and Smoothing

Scans may have surface “jitter” or spikes due to lighting or motion.

Tools to use:

• Smooth filter: Relaxes jagged geometry

• Remove isolated pieces: Deletes floating geometry

• Shrinkwrap or remesh: Conforms surface to a smoother form

🛑 Avoid over-smoothing – you may lose surface detail!

🟪 6. Simplification / Decimation

Raw scans often have millions of polygons.

• Decimation reduces face count while preserving shape

• Use tools like “Quadratic Edge Collapse Decimation” (MeshLab)

• A lower-poly model is easier to edit, render, or slice

• Balance detail with file size and performance

🧠 Rule of thumb: ~50k faces is ideal for most printable models

🟫 7. Exporting Cleaned Meshes

Once cleaned, export in a suitable format for your next task:

📝 Always validate the exported mesh in a slicer or modeling tool before use.

🧠 Summary

Mesh cleanup is an essential skill for anyone working with scanned models. Whether you’re prepping for 3D printing or modeling, removing defects and optimizing your mesh ensures a smoother workflow and better results.

Mesh Cleanup Checklist:

✅ Remove stray or broken geometry
✅ Fill holes and close gaps
✅ Reduce polygon count without losing detail
✅ Smooth noisy surfaces carefully
✅ Export in the correct format for your workflow

📂 Optional Activities

Assignment:

1. Download a raw mesh from a scanner or 3D scan repository

2. Use MeshLab or Blender to:

   • Remove noise or fragments

   • Fill holes and make watertight

   • Simplify the mesh

3. Export the cleaned model and upload screenshots of before/after

📎 Additional Resources

• MeshLab Tutorials

• Blender Mesh Cleanup Guide (YouTube)

• Autodesk Netfabb STL Repair Tool

• Scan the World (Download Meshes)