Part 6 — UVs and baking
Unwrapping, seams, texel density and packing, then baking high-poly detail into normal and other maps.
UV mapping
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
Baking
- BakingTopicTransferring detail and information from a high-poly mesh (or the low poly itself) into textures; what each common map stores and is used for, the main bakers, a reliable workflow, naming, anti-aliasing and resolution.
- Bake cageKey termAn inflated copy of the low poly that tells the baker where rays start and which direction they travel; averaged cages avoid gaps at hard edges, and a cage that is too large or too small causes most projection errors.
- Bake groups and exploded bakesKey termTwo ways to stop parts of a model from baking onto each other; pair each low-poly part with its own high poly by group or by name, or move the parts apart before baking, and handle the lost contact shadows.
- Tangent space and MikkTSpaceKey termThe per-vertex frame a normal map is read in; why the baker and engine must calculate it identically (MikkTSpace), what a synced workflow is, and which engines expect OpenGL (Y+) or DirectX (Y−) green channels.
- Fixing baking artefactsGuideA diagnostic guide to the common errors in baked maps (skewing, waviness, seams, ray misses, intersections, AO bleeding, gradients and jagged edges) with the cause of each and the fixes, in the order to try them.