Why and When UVs Can Cross the 0–1 (UDIM) Tile Boundary in Tiling Materials

The key difference comes down to the purpose of the UVs and whether the textures are baked uniquely or tiled.For hero assets or general props using baked textures (often within the 0–1 space or UDIM tiles), UV shells should remain inside their assigned tile and not cross borders. This is important because baking generates texture information specific to that UV layout. If UV shells cross tile borders, padding and mipmaps can cause texture bleeding, resulting in visible seams or artifacts. Keeping UVs within the tile ensures clean baking and proper texture sampling.In contrast, during the blockout phase or when using tiling materials, UVs can safely cross tile boundaries or sit on borders. This works because tiling materials are designed to repeat seamlessly, and the engine samples them in wrap/repeat mode. In this case, UVs are not tied to unique baked texture information but instead reference a repeating pattern, so crossing boundaries does not introduce baking errors.In practice, the rules are:• Keep UV shells strictly inside the 0–1 or UDIM tile when using baked, unique textures.• Allow UVs to extend beyond the 0–1 space when using tiling/repeating materials.• Avoid placing UV edges exactly on borders when baking, to prevent mipmap bleeding.• Ensure proper padding when baking textures to reduce artifacts.• For tiling materials, prioritize consistent texel density and seamless alignment rather than tile containment.In the context of this course, the blockout and modular workflow uses tiling materials for flexibility and efficiency, which is why UVs can extend beyond the tile. Later, when creating final assets with baked or unique textures, UVs are properly organized within their respective tiles.So yes, the main distinction is whether the texture is baked uniquely or sampled as a repeating tiling material.

Questions on topology cleanliness and beveling during the detailing stage

Great question — what you’re noticing mainly comes from the difference between a character-modeling mindset and a real-time environment art workflow. In this course, once the blockout is approved, the refinement stage focuses on silhouette, readability, and final rendering in Unreal Engine, not animation; the assets are static, and Unreal triangulates everything on import anyway, so non-quad topology or occasional n-gons are not an issue as long as they’re on flat, well-controlled surfaces with clean UVs. Any potential risks are further minimized through a workflow built around simple UVs, tiling textures, procedural materials, and decals, which greatly reduces shading or texturing artifacts. As for bevels, finishing them with just two edge loops is usually sufficient because their main purpose is to break hard edges and catch light, with normal maps doing most of the heavy lifting; adding more supporting edges would often be unnecessary and less optimized. Your understanding is absolutely valid, but it comes from a deformation-focused context — the course gradually shows when clean topology really matters and when it can be simplified without affecting visual quality or performance.