Decimate makes a mesh lighter: it takes away the triangles that matter least to the shape and keeps the ones that carry it, until the mesh has as many triangles as you ask for. Use it to bring a heavy sculpt down for export, printing or sharing, or to make a light copy to keep working on. It works on any mesh in the studio, open or closed, from a few thousand triangles to the largest the studio holds.

Using it

Open Tools ▸ Decimate…. A small window opens beside the panel, and the view shows the active layer as it will look after decimating. Orbit, pan and zoom as usual to look it over.

  • Keep — the share of the triangles that stays. Drag the slider; the count follows as you drag, and the view shows the result when you let go.
  • Triangles — type the exact number you want and press Enter.
  • Keep borders — open edges stay exactly where they are. Off lets them be reduced too, along the edge.
  • Keep Mesh Set borders — the lines between Mesh Sets stay exactly where they are. Available when the layer has Mesh Sets.
  • Protect masked — masked areas keep every triangle. Available when the layer has a mask.
  • New layer — the result becomes a new layer and the original is hidden, untouched. Off, the result replaces the layer.
  • Apply decimates the whole mesh. Cancel (or Esc) closes the window and changes nothing.

The counts at the top read now → after. When the options hold the mesh back (a large masked area, many Mesh Set borders), the window says the lowest count it can reach with them.

What it keeps

  • Shape. Flat and gently curved areas lose triangles first; ridges, creases and fine detail keep theirs longest.
  • Paint, mask and Mesh Sets. Decimate keeps a selection of the original points rather than making new ones, so every point that stays keeps exactly its colour, roughness, metalness, mask and Mesh Set. Painted edges and mask edges also steer which triangles go.
  • One Undo. Replacing a layer is one step: Undo brings the layer back exactly as it was, its subdivision levels included. With New layer, Undo takes the new layer away and shows the original again.

The result is a single level. When the layer keeps subdivision levels above the one you are on, replacing it asks first, as Remesh does; New layer leaves them on the original.

Big meshes

Decimate has no size limit of its own. It works in the background, so the studio stays responsive and the window shows its progress.

  • On the graphics card. Meshes above a quarter of a million triangles are reduced on the graphics card, which is faster there and keeps the shape at least as closely. If the card cannot take a mesh (not enough graphics memory, for example), the processor finishes the job; nothing changes for you.

  • The preview stays quick. On meshes above 400,000 triangles, Decimate makes a light copy of 300,000 triangles when the window opens and draws the preview from it, so moving the slider takes a fraction of a second. If you keep more than that, the view shows the light copy and says so. Apply always works on the full mesh.

  • Very large meshes are worked in pieces. A mesh of tens of millions of triangles is cut into slices that are reduced side by side and joined again exactly, then the joined mesh is finished in one pass, so the count lands where you asked.

  • Live Topology is switched off first, as for Remesh.

Tips

  • Decimate after sculpting, not before: it is for making a finished mesh lighter, not for even topology. For clean, even quads to keep sculpting on, use Remesh or Reflow.
  • Use New layer to compare: hide and show the two layers to see what changed.
  • To keep a face or a detail crisp while the rest goes light, mask it and leave Protect masked on.