UV Unwrapping of 3D Graphics Models
UV unwrapping—technically the most underappreciated part of the pipeline. An artist spends a week sculpting, a day on retopology, then UV is done in an hour "just to have it." Then they bake a normal map and see blurry seams on the face, stretched textures on the side, and seam right down the middle of the forehead.
Good UV unwrapping is invisible. Bad UV—noticeable on every screenshot.
Where UV problems originate
Texel density. The most common mistake—uneven texel density. Face gets the same UV space as the back, though the face is the viewer's focal point. On a 2048×2048 texture this is the difference between a readable face and a blurred mask. Tools like Rizom UV or Blender's built-in Texel Density Checker let you measure and normalize density by priority zones.
Stretching. UV island distortion causes texture distortion on the surface. Organic forms (head, hands) are especially sensitive—even 5–10% stretch is noticeable on diffuse textures and doubled on normal maps. Checked via Checkerboard Shader and Stretch Visualization in Blender/Maya.
Seam artifacts during baking. UV island seams produce dark or bright stripes during Marmoset Toolbag and Substance Painter bakes. Cause—incorrect padding between islands. Standard for 2048×2048 is minimum 4px padding (better 8px for mobile with mip-levels). At 1024×1024—4px minimum.
Overlapping islands. If UV islands overlap, baking creates artifacts—obvious. Less obvious: overlap is deliberately used for symmetric objects (boots, pauldrons). But this works only if lighting and baking don't create visible differences between mirrored parts. In reality—almost always does.
How professional UV unwrap is done
We work in Rizom UV for complex organic objects and Blender UV Editor for more straightforward tasks. Maya UV Toolkit when the model is already in a Maya pipeline.
Planimetric seam placement. Seams are cut through hidden and visually non-priority zones: back of neck, inner thighs, sole, armpits. Rule: seam where camera lands least often. For weapons—end surfaces of handle and bottom edge of blade.
Unwrap. In Rizom UV use Unfold3D algorithm with subsequent manual correction of problem zones. Full Unfold3D automation gives good starter results, but boundary islands (ears, fingers, fastening details) need manual intervention.
Packing. Automatic packing in Rizom UV (or UVPackmaster for Blender) with manual priority placement. Face, hand palms, visible details—in main UV space with maximum area. Soles, inner surfaces—compact zone with minimal UV space.
Texel density normalization. After packing normalize density by critical zones. Face and hands—priority. Other surfaces—relative normalization with 10–15% tolerance.
Verification. Checkerboard + Stretch map. If checkerboard squares are deformed that's stretch. If seams are visible they need cutting or repositioning.
For UDIM workflow (multiple UV tiles) the process is identical, but islands are distributed by tiles consciously: head—tile 1001, body—1002, hands—1003. This is required for high-res characters in Unreal Engine 5 with Nanite or rendering pipelines for cinematics.
Timeline guidelines
| Object | Complexity | Timeline |
|---|---|---|
| Simple prop (weapon, tool) | low | 2–6 hours |
| Hard-surface character / vehicle | medium | 1–3 days |
| Organic character | high | 2–4 days |
| Full character with UDIM (4–6 tiles) | very high | 3–6 days |
Timeline is for UV unwrap without texturing. Cost is calculated individually.
What needs to be provided
- Final low-poly mesh (FBX or OBJ) with agreed topology
- Target texture atlas size (2048, 4096, UDIM)
- Information on what will be baked (normal map, AO, curvature)
- Requirements for material slot count (single texture or multiple)