An algorithm that reduces the polygon count of a mesh while preserving the original shape as closely as possible by collapsing short edges and merging coplanar faces.
Mesh decimation (or simplification) reduces polygon count using algorithms like Quadric Error Metrics (QEM, used in Blender's Decimate modifier and MeshLab). QEM assigns a quadric error metric to each edge collapse operation and greedily collapses the edges with lowest error first. The target is a mesh that is geometrically similar to the original but with a fraction of the faces. Preserves important features (sharp edges, corners) better than uniform subdivision removal.
Use decimation before slicing when: a sculpted mesh has millions of triangles exceeding slicer memory limits, an imported CAD file was over-tessellated, or a 3D scan needs to be reduced for printability. In Blender: Modifiers → Decimate → Collapse, set ratio 0.1–0.5. In MeshLab: Filters → Remeshing → Quadric Edge Collapse. Aim for the minimum polygon count that preserves visible detail at print scale: check by zooming to 1:1 scale in the slicer.
Aggressive decimation (ratio < 0.05) can destroy fine surface features: always compare before/after at print scale. Decimation does not improve mesh topology (non-manifold, inverted normals): fix these before decimating. The resulting mesh may still be non-manifold if the input was; decimation does not guarantee watertight output. Always verify the decimated mesh in the slicer before sending to printer.
Related terms: Polygon Count, Mesh Topology, Retopology, Tessellation
| Field | 3D design, 3D printing |
|---|---|
| Also called | polygon reduction, mesh simplification, decimation |
Engineer, author of The Big Book of 3D Printing and additive manufacturing expert