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Decimate vs retopology: which should you use?
Decimation is fast and messy; retopology is slow and clean. How each works, what they do to UVs and deformation, and when to use which.
3 min read
Quick answer
What is the difference between decimation and retopology?
Decimation automatically removes polygons from an existing mesh, quickly but with messy, triangulated topology. Retopology builds a new, clean mesh over the original, usually in quads with edge loops placed for shape and deformation. Decimate static props and background objects; retopologise anything that animates, is seen up close or needs good UVs.
Both reduce polygons, differently
You have a mesh with too many polygons, a sculpt, a scan or an AI generation, and you need fewer. There are two families of fix:
- Decimation removes polygons from the mesh you have.
- Retopology builds a new mesh on top of it.
Same goal, very different results.
Decimation
Blender's Decimate modifier has three modes, as described in the Blender manual:
- Collapse merges vertices "progressively, taking the shape of the mesh into account". A Ratio sets how much survives: 1.0 leaves the mesh alone, lower values remove more.
- Un-Subdivide reverses subdivision. It works best on grid-like meshes.
- Planar dissolves edges between faces that are nearly flat, controlled by an Angle Limit.
Strengths: one slider, seconds of work, preserves the overall shape well at moderate ratios.
Weaknesses:
- Produces irregular triangles with no edge flow.
- Doesn't place edge loops where joints bend, so animated models deform badly.
- Can damage UVs and textures, especially at low ratios.
- Hard to edit afterwards.
Retopology
Retopology means building a new surface that follows the original's shape, usually in quads, with edge loops placed deliberately: around eyes and mouths, at elbows and knees, along hard edges.
It can be manual (snapping new geometry to the original surface in Blender), assisted (add-ons and tools like QuadriFlow, Blender's Remesh with Quad mode), or automatic (as Vi3W does on every generated model).
Strengths:
- Clean, predictable topology that's easy to edit.
- Edge loops where deformation happens, so animation works.
- Better UV unwrapping.
- You control exactly where density goes.
Weaknesses:
- Manual retopology takes hours for a complex model.
- Automatic retopology is quick but can't know which joints you'll animate.
Side by side
- Speed: decimate is seconds; manual retopology is hours; automatic is in between.
- Topology: decimate gives messy triangles; retopology gives clean quads.
- Animation: decimate is poor; manual retopology is best.
- UVs: decimate can break them; retopology needs new UVs but gives better ones.
- Editing later: decimated meshes are hard to edit; retopologised ones are easy.
Which should you use?
Decimate when:
- The object is static: rocks, rubble, props, background buildings.
- It's seen from a distance or is small on screen.
- You're making LODs from an already-clean model.
- You need a quick reduction for a prototype.
Retopologise when:
- The model will be rigged and animated.
- It's a hero asset seen up close.
- You need clean UVs for hand-painted textures.
- You'll keep editing the model.
A common combined workflow
- Start from the dense mesh (sculpt or AI generation).
- If it's a hero asset, retopologise.
- Bake detail from the dense mesh to the new one's normal map.
- Decimate the clean mesh to make LOD1, LOD2.
With AI-generated models
Vi3W retopologises every model automatically, so you start with a lighter mesh than a raw generation. For props, that's often enough. If you need fewer triangles still, a light Decimate is a quick finish. For characters that will animate, plan a manual pass on the joints; see why AI characters deform badly. Cleaning up an AI-generated model covers the full Blender routine.
Want to skip most of the reduction work? Generate in Vi3W and start from a retopologised mesh.
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