Subdivision levels
Subdivision levels let you sculpt one model at several resolutions, as with ZBrush's SDiv: block in the big forms on a light version of the mesh, add pores and wrinkles on a dense one, and go back down to change the silhouette without losing the detail. Every SubTool has its own levels.
Everything is in Tool > Geometry:
| Control | Shortcut | What it does |
|---|---|---|
| Divide | Ctrl+D | Adds a level above the highest one and steps to it |
| Smt | Smooths the next Divide (on by default) | |
| Lower Res | Shift+D | Steps one level down |
| Higher Res | D | Steps one level up |
| SDiv slider | Steps to any level (1 is the base cage) | |
| Del Lower | Deletes the levels below the current one | |
| Del Higher | Deletes the levels above the current one | |
| Reconstruct Subdiv | Finds a lower level for a mesh that was subdivided elsewhere |
Under the buttons the palette says where you are ("SDiv 3 of 5") and how many triangles the base and the top have. The SubTool list shows the level of every SubTool that has them ("SDiv 3/5").
Divide#
Divide (Ctrl+D) adds a level with four times the polygons. The lower levels stay, so you can step back down at any time.
- Quads stay quads. A mesh with quads is divided with Catmull-Clark subdivision: each quad becomes four quads, and a triangle among them becomes three quads. A mesh of triangles only (a sphere from New Sphere, a scan) is divided with Loop subdivision: each triangle becomes four.
- Smt (next to Divide) smooths the new level, rounding off the shape the way ZBrush does. Turn it off to divide flat: the new level keeps the hard edges and flat faces of the one below, for hard-surface pieces.
- Divide always adds the level on top. If you are at a lower level it steps to the highest first.
- Mask, polypaint, paint layers and UVs are interpolated onto the new level; polygroups and hidden faces carry over; sculpt layers are divided with the shape.
- How far you can divide depends on your computer's memory: about 160 million triangles with 32 GB (each triangle of a divided model takes about 90 bytes, plus some room while dividing). Divide says so when the next level wouldn't fit.
Stepping between levels#
Press Shift+D to step down and D to step up, or drag the SDiv slider. Each step is instant once you have visited a level; the first visit after a big edit lower down takes a moment on millions of triangles.
What happens to your sculpting when you change level:
- Detail survives. Each level stores its detail as a small offset from the smoothed shape of the level below, measured along that surface (its normal and tangents). Stepping up and down without sculpting gives back exactly the same mesh.
- Big changes low, detail follows. Sculpt, move or inflate at a low level and step up: the higher levels follow the new shape and the wrinkles, pores and scales you sculpted on them ride along on top.
- Detail edits show up below. Sculpt at a high level and step down: the lower levels take on a softened version of the change, so the silhouette stays honest whichever level you look at. Fine detail is too small for a low level and only shows as a gentle swelling there.
What follows the levels#
| When you change it at one level | |
|---|---|
| Shape | Carried up as detail, softened down (see above) |
| Sculpt layers | Each layer has its own detail on every level, kept relative to the surface like the shape's: rotate or reshape a low level and a layer's wrinkles turn and bend with it. Weights apply to all levels. See Layers and subdivision levels |
| Mask | Copied down to the vertices below, interpolated up where it changed |
| Polypaint and paint layers | As the mask: paint at a low level for broad colour, at a high level for detail. Painting low only changes the higher levels where you painted |
| Polygroups, hidden faces | Copied down to the parent faces, inherited up by the faces they contain |
| UVs | Copied down and interpolated up |
| Texture | Shared by every level (it lives on the UVs) |
Clearing the mask, removing a layer or deleting the paint layers does it on every level.
Del Lower and Del Higher#
Del Lower deletes the levels below the current one: the current level becomes the new base cage (SDiv 1). Del Higher deletes the levels above, and the detail sculpted on them. Both are undoable. Deleting down to a single level leaves an ordinary mesh.
Reconstruct Subdiv#
A model that was subdivided in another application (or exported from SculptForge at its top level) comes in as one dense mesh. Reconstruct Subdiv finds the mesh it was subdivided from and adds it as a new lowest level, keeping the dense mesh exactly as it was. Press it again for more levels.
- It works at the lowest level (SDiv 1).
- The mesh must be a regular subdivision: all quads from Catmull-Clark subdivision (Blender's Subdivision Surface, Maya's Smooth, ZBrush's Divide), or all triangles from Loop subdivision. Otherwise it says so and leaves the mesh alone.
- The vertices of the new lower level sit on the dense mesh's corner vertices, as in ZBrush.
Undo, projects and exporting#
- Undo (Ctrl+Z) is one step per stroke at any level, and one step per level change, so undo walks back through your strokes and level changes in the order you made them. Divide, Del Lower, Del Higher and Reconstruct are single undo steps. Steps share the levels they didn't change, so they cost little memory.
-
Projects (
.sfproj) save every level of every SubTool and open at the level you saved at. They use project format 5 (sculpt-layer detail relative to the surface), so older SculptForge versions ask you to update before opening them. Projects saved with format 4 open as before and are converted as they load. -
Exports and GoZ write the current level. To write another one, step to it first, or use the
subdiv_exportcommand (subdiv_export path=base.obj level=1writes the base cage of every visible SubTool, in any export format). LODs and Send to Unreal start from the current level too. - Tools that rebuild the mesh (Voxel Remesh, Decimate, QRemesh, Subdivide, Delete hidden, merging and splitting SubTools) work on the level you are on, including what you just sculpted there, and make a new mesh without levels: that level becomes the new base. The status line says so, e.g. Subdivision levels removed: SDiv 3 of 5 kept as the new base (undo restores them). Ctrl+Z brings every level back, at the level you were on. Merging and splitting SubTools can't be undone (as in ZBrush), so step to the level you want to keep first, or save before.
Commands#
Every control is a command you can run in the console, from a script or over MCP (see Scripting):
| Command | What it does |
|---|---|
subdiv_divide smooth=true | Divide; smooth=false divides flat (Smt off) |
subdiv_level level=2 | Step to a level (1 = base) |
subdiv_lower, subdiv_higher | Lower Res, Higher Res |
subdiv_delete_lower, subdiv_delete_higher | Del Lower, Del Higher |
subdiv_reconstruct | Reconstruct Subdiv |
subdiv_info | List the levels and their triangle counts |
subdiv_export path=base.obj level=1 | Export the visible SubTools at a level |
Speed and memory#
Measured on an Apple M1 Pro (Asahi Linux), a cube divided four times to 6.5 million triangles:
| 1.6M triangles at the top | 6.5M triangles at the top | |
|---|---|---|
| Divide to the top level | 0.4 s | 4.3 s |
| Step down / up between visited levels | 1-4 ms | 0.1-45 ms |
| Step down right after sculpting the top | 0.05-0.13 s | 0.2-0.6 s |
| Step up after reshaping the base | 0.05-0.15 s | 0.6 s |
| Memory for all levels | 120 MB | 480 MB |
SculptForge keeps the two levels you visited last ready to show, so going back and forth between a low and a high level (the usual rhythm) is instant. Only the active SubTool keeps them: selecting another SubTool frees that memory (50-170 MB for a SubTool with 1.8 million triangles at the top), and the first level change after you come back takes a moment longer (about 0.1 s at that size) while the level is prepared again.