Blender's Decimate modifier can take a vertex group to control where it simplifies more or less — but nothing builds that vertex group for you. Today that means manually marking seams and manually painting weights before you even start. SeamSmith automates that setup: it detects the mesh's major shape lines, builds the protection weighting from them, runs decimation in a way that still hits your target count, and chains straight into unwrap and pack.

No, and we don't want to oversell it. It drives Blender's existing Decimate (Collapse) modifier through its vertex-group input — it doesn't replace Blender's simplification math with a custom boundary-constrained one. For most organic, sculpt-style meshes the result is noticeably better than decimating blind, but it's an approximation, not a from-scratch algorithm.

It's built and tuned for organic, sculpted meshes (rocks, creatures, foliage, terrain chunks). Hard-surface and CAD models usually already have clean, intentional topology and very different edge-angle patterns, so the automatic seam detection is less likely to help there — you're generally better off with a hard-surface-focused decimation tool for that kind of asset.

A first pass runs with seam protection applied. If a large portion of the mesh ends up protected and the result is still well above your target, a second, unweighted pass runs automatically to force it down to the target count. You'll see "forced 2nd pass" in the result summary when this happens.

You position a visible plane (either along the object's local X/Y/Z axis, or a custom plane you place and rotate yourself) along the model's real line of symmetry. SeamSmith cuts the mesh there, decimates only that half, snaps the cut boundary exactly back onto the plane, and uses a Mirror modifier to rebuild the other half — so both sides are guaranteed identical, instead of hoping a symmetric input mesh decimates symmetrically (it often doesn't).

Not currently. Only a single flat cutting plane is supported per run.

Seam detection and the protection mask are fully vectorized with numpy, so that part stays fast even at high density — typically well under a second. Overall run time still depends on how much of the mesh the Decimate modifier itself has to process, and on how large the output is before unwrapping, which is why the forced second pass matters: it keeps the mesh handed to UV unwrapping close to your target size instead of leaving it unexpectedly large.

For a lot of organic props, yes — the automatic unwrap and pack is usable as-is. For complex or hero assets, treat it as a strong starting point rather than a final pass; manual touch-ups on specific islands are still normal practice.

No. Every run works on a duplicate (named with a `_LOW` suffix). Your source mesh is left exactly as it was — the only exception is the **Preview Seams on Source** button, which marks seam flags directly on the source mesh so you can inspect them before committing to a run (it does not change geometry).

Blender 4.0 and newer, tested on Blender 5.0, on Windows, macOS, and Linux.