Topology & Remeshing

Topology & Remeshing

During freeform concept sculpting, geometry frequently stretches, twists, or runs out of polygon density when pulling out long extrusions (such as horns, fingers, or limbs). OxyBrush provides several topology-rebuilding tools to keep your geometry clean and uniform: Voxel Remeshing, Dynamic Topology, and Quadric Decimation.

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Voxel Remeshing (Ctrl + R)

Voxel remeshing is the fastest way to turn any complex, self-intersecting, or stretched geometry into a single uniform, manifold watertight mesh.

How It Works

1. OxyBrush converts the existing surface into a Signed Distance Field (SDF) voxel grid.
2. It resamples the volume at a fixed cubic grid cell size.
3. It extracts a new, perfectly uniform triangle/quad mesh using Dual Contouring / Marching Cubes.

How to Use Voxel Remesh

1. Open the Mesh / Topology panel on the right sidebar.
2. Set your Voxel Size (or use the visual eye-dropper to pick density directly on the mesh).
   • Larger voxel size (e.g. 0.05): Blurs small details, ideal for fast blockout silhouette merging.
   • Smaller voxel size (e.g. 0.005): Preserves crisp facial landmarks and edge creases.
3. Toggle Preserve Sharp Features if working on hard-surface assets.
4. Press Ctrl + R (or click Remesh).

Combining Pieces with Voxel Union

Voxel remeshing is also a powerful boolean union engine:

• If your scene contains multiple intersecting pieces (e.g. a torso piece, two arm cylinders, and a head sphere):
  1. Select all pieces in the Outliner.
  2. Right-click and choose Voxel Union.
  3. The intersecting meshes fuse into a single seamless, hollow-free skin with no interior intersecting faces—ideal for 3D printing!

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Dynamic Topology (Dyntopo)

While voxel remeshing operates globally across the entire mesh, Dynamic Topology operates locally directly under your brush cursor in real time.

• As you stroke with the Snake Hook or Clay brush, OxyBrush dynamically subdivides long edges to add resolution where needed.
• In areas where you stroke with a large Smooth brush, OxyBrush automatically collapses tiny edges to optimize density.

Dyntopo Detail Modes

• Brush Detail: Polygon density scales with the brush radius. Small brushes add dense detail; large brushes create broad, low-poly forms.
• Constant Detail: Polygon density is fixed in world-space units regardless of brush size or camera zoom.
• Relative Detail: Polygon density adapts based on the current camera zoom level.

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Quadric Decimation (Mesh Optimization)

When you are finished sculpting a 5-million polygon model and need to export it for game engines, rigging, or 3D slicers (such as Bambu Studio, PrusaSlicer, or Cura):

1. Go to the Topology panel and scroll to Decimation.
2. Select your target:
   • Target Triangles: Specify an exact target number (e.g., 100,000).
   • Reduction Ratio: Specify a percentage (e.g., 20% of original count).
3. Check Preserve Boundaries and Preserve Vertex Colors.
4. Click Decimate Mesh.

OxyBrush uses a high-performance Garland-Heckbert Quadric Error Metric (QEM) algorithm. It intelligently collapses coplanar flat areas down to very few polygons while concentrating dense triangles along curved silhouettes, creases, and fine surface landmarks.

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Workflow Comparison Guide

Feature	When to Use	Preserves UVs?	Preserves Multires?
Multires Subdiv (Ctrl+D)	High-end character modeling, preserving base UVs, baking normal maps	Yes	Yes
Voxel Remesh (Ctrl+R)	Early blockout, fusing intersecting primitives, fixing non-manifold geometry	No (generates fresh mesh)	No (flattens to single level)
Dynamic Topology	Freeform sketching, rapid concept ideation, sculpting without worrying about poly budget	No (dynamically tessellates)	No
Quadric Decimation	Final asset export, game LOD generation, reducing file size for 3D printing	No	No