Merge Window
The Merge window welds vertex points together on the materials you have selected, so parts that were modelled or exported as separate pieces become one continuous surface before you remesh them. Open it from Window → Merge, or press M by default (the same key closes it again). It is a free-floating window you can leave open while you work.
What it works on
Merge works on whatever materials are currently toggled on in the Material Tools window’s materials list (see Select by Material). The top of the Merge window shows how many are selected; with none selected it tells you to toggle some in Material Tools first, and the Merge button is disabled.
The weld is always applied to the Loaded Mesh — the imported model — not to the Generated Mesh. Use it before you create new topology, so the remesher sees one surface instead of several touching pieces.
Controls
| Control | What it does |
|---|---|
| Automatic | Merges vertex points that share the exact same coordinates into one point. Polygons keep their current texture assignment. This is the default mode, and the safe choice when the pieces were exported with matching edges. |
| Fixed Distance | Merges every vertex point within the given distance of another into one point. Use it when pieces almost meet but have a small gap. Merging chains: if A is close enough to B and B to C, all three become one point even if A and C are further apart. |
| Distance field and um / mm / cm / m | Shown only in Fixed Distance mode. The merge radius, in the unit you pick (micrometres, millimetres, centimetres or metres). The default is 1 cm. Negative values are not allowed. |
| Merge | Welds the vertex points on the selected material(s) using the chosen mode. |
Points that are already connected to each other through the selected polygons are left alone, however close they are. That matters because a UV-mapped model normally has duplicate points along every UV seam; Merge only closes genuine gaps between separate pieces and leaves those seams intact. A merged point takes the position of one of the points it replaced — nothing is averaged or moved.
After merging
The status bar reports how many vertex points were merged, or that no vertex points were close enough to merge (in which case nothing changes). After a successful merge:
- The Loaded Mesh’s normals are recalculated, so the welded areas shade smoothly.
- The number of polygons, their materials and the model’s size are unchanged; only the vertex count drops.
- Anything stored per vertex on the Loaded Mesh is reset, because the old vertex numbering no longer exists: Vertex Density Paint, any painted vertex mask, and the model’s skin weights.
- Sculpt undo history on the Loaded Mesh is cleared.
Merge window vs. Merge Selection
Merge Selection in Material Tools (see Merge Selection & Pass Through) can do the same weld through its Merge Points option, with the same Automatic and Fixed Distance settings. The difference is that Merge Selection always asks for a name and creates a named group from the selected materials. The Merge window just welds the points: no name prompt and no group. Use it when you want to join pieces without reorganising your materials.
The two share their mode, distance and unit settings. Clicking Merge Selection resets them to Automatic and 1 cm, so check the Merge window’s settings before you click Merge afterwards.