UDIM
Multi-tile UV layout
Also known as: UDIM tiles · Tiled UVs
Definition
UDIM is a multi-tile UV layout standard where each "tile" is a separate texture file numbered 1001, 1002, 1003 and so on. Instead of cramming an entire character's UVs into one 4K texture, UDIM lets the artist split the head onto 1001 (its own 4K), the torso onto 1002, hands onto 1003 — increasing effective resolution without pushing one texture beyond practical sizes. Used heavily in film and high-end game character pipelines.
In production
Substance Painter, Mari, and modern ZBrush (via its UV Master and GoZ workflows) handle UDIMs natively, letting an artist paint across tile boundaries as if working on one continuous surface even though each tile bakes out to its own file, typically named following the pattern characterName_1001.png, characterName_1002.png, and so on. Real-time engines like UE5 consume UDIMs via Virtual Texturing, which streams in only the texture tiles visible on screen at the resolution actually needed. For mobile or lower-spec games, studios stick with single-tile UVs and texel-density compromises instead, since UDIM workflows assume texture streaming and VRAM budgets that mobile GPUs and older consoles can't support. A common mistake is letting UV islands cross a tile border, which most bakers and game engines simply cannot handle correctly, splitting the island's texture data across two files; RizomUV and UV layout tools flag border-crossing islands explicitly so artists can pack around this constraint.
