UV Seams — Where to Place Them to Minimize Visible Stretching
UV seams are the cuts you make in a 3D mesh to unfold it flat for texturing. Every seam is a potential visibility problem — and every area without seams is a potential distortion problem. This guide explains how to make smart seam decisions for game assets so you get clean UVs and invisible seams.
What are UV Seams?
A UV seam is an edge on the 3D mesh where the surface is "cut" to allow it to unfold flat into 2D UV space. Think of it like cutting a cardboard box apart so it lies flat — you have to make cuts in specific places so the whole thing unfolds without overlapping.
Without seams, most 3D surfaces can't be unfolded without severe stretching or distortion. Seams give you control over where that distortion budget is spent and where island boundaries appear. But every seam is also a potential artifact — a subtle visible line where the texture doesn't perfectly continue across the boundary.
Placement Principles
Good seam placement balances two competing needs: putting seams where they're needed to reduce distortion, while hiding them where the player won't notice.
Place seams where the player won't look
Undersides, back faces, inside seams of clothing, bottom of feet, areas permanently facing away from the camera. A seam the player never sees can never be a problem — put them in these areas first.
Follow natural breaks in the design
Panel lines, material boundaries, fabric seams, weld lines — places where the design already changes are natural seam positions. The texture naturally transitions at these points anyway, making any seam misalignment invisible.
Avoid seams on silhouette edges
The outer boundary of the mesh as seen by the player — placing a seam here makes it prominently visible as a line on the most visible part of the asset. Move seams inward from silhouette edges whenever possible.
Cut where topology changes abruptly
90-degree corners, transitions between surface types, and areas where edge loops change density are natural seam positions — the topology already breaks here, so a UV seam at the same location adds no additional visual disruption.
Use the minimum seams needed
Every seam is a risk. Add only as many as needed to keep distortion low. Start with the minimum and add more only where the distortion check reveals it's necessary.
Seam Placement by Asset Type
Different asset types have natural seam positions based on their shape and how the player views them.
| Asset Type | Good Seam Locations | Avoid |
|---|---|---|
| Character body | Armpits, inner thighs, back of neck, along spine, inside of arms | Face, front of hands, centre chest, prominent clothing edges |
| Weapon (gun) | Underside of barrel, inside of grip, back of stock, trigger guard interior | Top rail, front sight, trigger face, any surface the player stares at |
| Box / crate | Bottom edges, rear face edges, underside corners | Front face, visible top, forward-facing corners |
| Vehicle | Undercarriage edges, wheel well interiors, door jambs, engine bay gaps | Door panels, hood, windshield pillars, any painted body surface |
| Cylindrical prop (barrel, pipe) | A single vertical seam along the back, away from camera-facing side | Front-facing edge of the cylinder |
| Character head | Behind and under the ear, at the hairline on the back of the head | Anywhere on the face, front of neck, top of head |
Minimizing Distortion
UV distortion (stretching) occurs when a UV island can't unfold flat without some areas being compressed or stretched relative to the real surface. Distortion makes textures appear stretched in one direction — checker squares appear rectangular instead of square, surface patterns look warped.
Low distortion
UV island unfolds close to flat. Checker squares appear roughly square across the whole island. Textures look correct and undistorted on the mesh surface at any angle.
High distortion
UV island forced flat with significant stretching. Checker squares appear rectangular or skewed. Textures look stretched on the mesh — immediately noticeable on any regular pattern or grid texture.
How to check and fix distortion
Apply a checker texture
A checkerboard is the standard distortion test. Apply one and look at the mesh — any area where squares appear elongated, compressed, or skewed has distortion. The more distorted the squares, the worse the stretching.
Add more seams in high-distortion areas
More seams give the unfold algorithm more freedom. A curved surface that distorts when unwrapped as one island may unfold cleanly when split into two or three islands along the curve. Add seams in the areas showing the worst distortion first.
Run UV relaxation / Minimize Stretch
Most UV tools include a relaxation solver that redistributes distortion more evenly across the island. In Blender's UV editor, press E while in the UV Editing workspace to run the stretch minimisation solver. It iterates the unwrap to reduce peak distortion values.
Practical Seam Workflow
This is the order of operations that produces the cleanest UV layouts consistently.
Mark seams at hard geometric edges first
These are required seams anyway for the hard edge / seam matching rule. Mark all 90° corners, panel line breaks, and material boundary edges as seams first. This gives you a starting point without worrying about distortion yet.
Unwrap and check distortion
Run the unwrap with just the required seams. Apply a checker texture and look at the mesh. Make note of any areas with heavy distortion — those islands need additional seams.
Add strategic seams where distortion is high
Add seams to the worst distortion areas, then re-unwrap. Each addition should reduce the peak distortion in that area. Continue until the checker looks acceptable everywhere.
Check seam visibility from player viewpoints
Rotate around the asset from the angles the player will most commonly see it. Any seam that falls prominently in a player-facing position should be moved to a less visible location — even if it means accepting slightly more distortion elsewhere.
Final unwrap and pack
Once seams are finalised, run a final unwrap and pack the islands with correct padding. This is the UV layout that goes into Trumble for baking and painting.
Seams and Trumble
Trumble's 3D painter lets you paint directly across UV seams on the mesh surface — the brush wraps correctly across island boundaries in 3D space, so you don't need to manually stitch seams in the 2D texture view. This dramatically reduces the visibility of seams in painted textures.
However, for baked maps (normal, AO, curvature), seam placement still matters significantly. Baked maps are generated per-island and stitched at boundaries — a seam in a prominent position will always show a slightly visible transition, regardless of the baking software. Good seam placement before importing to Trumble produces cleaner baked results that require less post-bake cleanup.
Paint directly on the mesh in 3D — Trumble handles seam wrapping automatically. No need to manually match colors at seam boundaries in 2D.
Apply a checker in Blender and verify seam positions before importing. Moving seams after baking means rebaking — fix them first.
Trumble automatically applies edge dilation to all baked maps, reducing the visibility of seam boundaries without any manual configuration.