The 3D Handbook
Part 6 — UVs and baking
Chapter

UV mapping

Read these pages in order, or jump to the one you need.

  1. UV mappingTopicHow a 3D surface is flattened into 2D texture space; projections and unwrapping methods; unique, tiling, trim and overlapping layouts; UV channels; and the main tools, with a crate unwrapped step by step.
  2. UV seams and islandsKey termSeams are the cuts that let a 3D surface lie flat; islands are the flat pieces they create. Where you put seams decides how visible they are, how much the texture stretches and how well the islands pack.
  3. Checker mapsKey termA test texture of evenly sized squares, applied to a model to reveal UV stretching, uneven texel density, flipped islands and badly placed seams before any real texturing starts.
  4. Texel densityTopicHow many texture pixels cover one metre of surface; how to calculate it, how to pick a value for first-person, third-person and top-down games, how to check it in common tools, and when to break the rule.
  5. UV packing and paddingTopicHow to arrange UV islands so they use as much of the texture as possible, how much space to leave between them at each resolution and why mipmaps decide that, what dilation does, and which islands deserve the most space.
  6. UV mirroring and stackingKey termLetting mirrored or repeated parts of a mesh share the same UV space to save texture resolution, and how to bake, light and shade such layouts without errors.
  7. Lightmap UVsKey termA second UV set where every face has its own space inside 0–1, with generous padding, so the engine can store baked lighting; how Unreal, Unity and Godot generate them, and when you no longer need them.
  8. UDIMsKey termA tile system that spreads one mesh's UVs over several 0–1 squares, each with its own texture; common in film, increasingly used for games, and supported in Unreal through virtual textures.