UV Packing Tips — How to Maximize Texel Density
How efficiently you pack UV islands directly determines how much texture detail your asset gets for a given resolution. Wasted UV space is wasted texture resolution — and wasted resolution means a blurrier, less detailed final asset. These techniques help you pack like a professional.
What is UV Packing?
UV packing is the process of arranging all UV islands from a 3D mesh into the 0–1 UV space as efficiently as possible — fitting them together tightly while maintaining adequate padding between islands and at the texture border.
The goal is to maximize the proportion of the texture that's occupied by actual mesh surface. A well-packed UV layout might use 85–92% of available UV space. A poorly packed one might waste 40–50% on empty gaps. That wasted space directly translates to wasted texture resolution — every pixel of empty UV space is a pixel that could have been giving your asset more detail.
Scale Islands Before Packing
Before running any auto-pack algorithm, UV islands must be scaled relative to each other proportionally to their real-world surface area. This is the step most beginners skip — and it causes the most visible quality problems.
If a large wall face and a tiny bolt head have the same UV island size, the bolt gets disproportionate resolution and the wall looks blurry in comparison. Every part of the asset should receive roughly equal texture resolution per real-world area — meaning larger surfaces need larger UV islands.
Unwrap all islands first
Get clean, low-distortion UV islands for every part of the mesh. Don't worry about final placement yet — just make sure each island unfolds correctly with minimal stretching.
Normalise texel density across all islands
Use a checkerboard texture to visually match checker square sizes across the whole mesh. Islands where the checker squares appear larger than others need to be scaled down. Islands where they appear smaller need to be scaled up. When all checker squares look the same size everywhere, your texel density is consistent.
Intentionally upscale priority areas
Once density is consistent, deliberately scale up UV islands for areas that deserve more resolution — the front face of a hero prop, a character's hands, the top of a surface the player sees most. This is a conscious artistic decision, not an error.
Then pack
Only once islands are correctly scaled relative to each other should you run Pack Islands. The packer's job is spatial arrangement — not scale decisions. Getting the order wrong means packing islands that are already incorrectly sized.
Packing Strategies
These techniques help you squeeze more usable resolution out of the same texture size.
Allow free rotation
Auto-packers that only allow 90° rotations leave significantly more wasted space than those that allow any angle. Enable free rotation in your packer settings — UVPackmaster for Blender and RizomUV both support this and achieve much tighter packs as a result.
Pack large islands first
Large islands can't fit neatly into irregular gaps left by small island placement. Pack the biggest islands first to establish the main structure, then fit smaller islands into the remaining space. Most professional packers handle this automatically, but it's worth understanding why.
Manually adjust after auto-pack
Auto-packing algorithms are good but not perfect. After running auto-pack, look for large wasted gaps — L-shaped spaces where a differently shaped island would fit. Manually move and rotate islands to fill these gaps. Small gains across many islands add up to meaningful resolution improvements.
Straighten irregular islands where possible
Curved or irregular island shapes waste more space between themselves and neighbouring islands. Where topology allows, straighten island boundaries — a slightly more rectangular island packs more efficiently than an organic one, even if the distortion cost is minor.
Getting Padding Right
UV padding is the gap maintained between islands and between islands and the texture border. Too little padding causes seam artifacts at mip-map transitions and during baking. Too much wastes resolution. The right amount depends on your output resolution.
| Texture Resolution | Minimum Padding | Recommended Padding |
|---|---|---|
| 512 × 512 | 2px | 4px |
| 1024 × 1024 | 4px | 8px |
| 2048 × 2048 | 8px | 16px |
| 4096 × 4096 | 16px | 32px |
The padding requirement stays proportional because mip-maps halve the texture resolution each level — at mip level 2, a 2048 texture is sampled at 512. The padding that looked adequate at full resolution can bleed at lower mip levels if it wasn't generous enough to begin with. Always pad for the lowest mip level you'll use in-engine.
Mirroring and Stacking Identical Islands
One of the most effective ways to reclaim UV space is to stack identical or mirrored UV islands directly on top of each other. If two surfaces are visually identical — like the left and right boot soles on a character — they can share a single UV island, halving the UV space needed for both.
Duplicate geometry (bolts, rivets, repeated panels) uses one UV island for all copies. Every copy shows the same texture — great for tiling detail elements.
Symmetric assets like character boots, shoulder pads, or symmetric props can have their mirrored halves share UV space — the mirrored side reads the texture in reverse.
Stacked UVs only work in UV channel 0. If the asset needs a lightmap (Unreal), UV channel 1 must have all islands unique and non-overlapping.
UV Layout in Trumble
Trumble reads and displays the UV layout from your imported mesh. Before starting any baking or painting, it's worth verifying the layout looks correct in Trumble's UV viewer — checking that coverage is high, padding is adequate, and no islands are overlapping unexpectedly.
The most important thing to confirm before starting work in Trumble: your UV layout is finalised. Changing the UV layout after baking invalidates the bake — the painted texture and baked maps no longer align with the mesh correctly. Get the pack right in Blender first, then import into Trumble.
Trumble's UV viewer shows the imported UV layout. Verify island coverage, check for overlaps, and confirm padding before starting to bake or paint.
Finalise your UV pack in Blender before importing to Trumble. Changing UVs after baking means rebaking — always pack before you bake.
Trumble's 3D painter lets you paint directly across UV seams on the mesh surface — the brush wraps correctly across island boundaries automatically.