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geo/Decimate

Reduces the triangle count of a mesh while preserving its appearance.

Topology

Simplifies each input triangle mesh with a quadric error metric (the polyReduce operation), stopping at the requested target or when the error budget is reached, whichever comes first. Topology is preserved: a watertight mesh stays watertight, and a non-manifold mesh (a raw scan) is decimated as-is without ever failing the cook. Typical use is taming dense imports — decimate a multi-million-triangle scan before feeding remeshing or simulation nodes. Other geometry types pass through unchanged.

Parameters

Name Type What it does
mode UInt8 RATIO · TRIANGLE_COUNT How the target is expressed: as a fraction of the input triangle count, or as an absolute triangle count.
ratio Float Fraction of the input triangle count to keep (0.25 keeps a quarter of the triangles).
count UInt32 Triangle count to aim for, clamped to the input count. Useful to bring inputs of very different densities to the same budget.
maxError Float Maximum simplification error, as a fraction of the mesh extent (0.01 = 1%). The node stops simplifying once reaching the target would exceed this.
lockBoundaries Bool Keep open-boundary vertices in place (rims, cut edges), so a decimated piece still lines up with neighbouring geometry.
pruneSmallComponents Bool Remove disconnected components smaller than the error budget — scan dust and floaters.
weld Bool Merge coincident vertices first, so seamed or triangle-soup inputs (STL scans) decimate as one connected surface. An input that is already a closed manifold is left alone — welding it could only pinch it, which would cost triangles and open holes.
allocator UInt8 TEMP · POOL · FLAT_POOL Which allocator backs the scratch buffers: a pool/flat-pool clears at end of cook, temp at end of frame.

See also

This page is generated from the engine, so it describes the release you can download. The same text is in the editor's Help panel next to the node itself.