Baking

Baking means calculating information about a mesh and saving it into a texture. Adobe's definition: "Baking is the name of the process about saving information related to a 3D mesh into a texture file" (Substance 3D Bakers documentation: What is baking?). In game art the most common case is the the high-to-low workflow: detail from a dense high-poly model is "transferred onto the second mesh UVs and then saved into a texture" (Substance 3D Bakers documentation: What is baking?).

The low poly stays cheap to render, while its normal map makes it shade as if it had all the high-poly bevels, bolts and panel lines. Other baked maps feed the texturing stage: Adobe notes that "many filters and materials can adapt to the specific geometry of a 3D mesh by looking at the baked textures" (Substance 3D Bakers documentation: What is baking?).

#How a bake works

For each pixel in the low poly's UV layout, the baker finds the matching point on the low poly and casts a ray. Substance's settings describe the search range: the frontal distance "controls how far above the low-poly surface the ray should start", and the rear distance how far below it should stop (Substance 3D Bakers documentation: Common parameters). Instead of distances you can use a cage, "essentially a copy of your low poly that expands outward to enclose the high poly" (Marmoset: The Toolbag Baking Tutorial). See bake cage.

This only works if the low poly has unique, non-overlapping UVs for the baked maps. See UV mapping and UV packing and padding.

#The maps and what they are for

In texturing software, maps such as AO, curvature and position mainly feed filters, generators and smart materials that adapt to the mesh's shape (Substance 3D Bakers documentation: What is baking?). Only ship the maps your engine's shader actually reads; often that is the normal map plus an AO channel in a packed texture.

#Bakers

For platforms and licence models, see UV, retopology and baking tools.

#A reliable workflow

1. Finish the low poly and its UVs. Hard edges must sit on UV seams; Marmoset: "break apart your UV islands along all hard edge borders" (Marmoset: The Toolbag Baking Tutorial). See smoothing, hard edges and smoothing groups.
2. Triangulate the low poly before baking and export. Adobe explains that there is "no standard" way to split quads and n-gons, so a different triangulation in the engine causes artefacts (Substance 3D Bakers documentation: Triangulating before baking). See triangulation.
3. Line up high and low. Both meshes in the same place, same scale, transforms reset.
4. Name the parts. Use matching _low and _high suffixes. See naming below and bake groups and exploded bakes.
5. Set up the cage or ray distances so the cage encloses the high poly. See bake cage.
6. Match the tangent space to the target engine. See tangent space and MikkTSpace.
7. Bake a quick, low-resolution test, check it on the model in a viewer, fix problems, then bake final quality.
8. Check in the engine with the final material, under lighting similar to the game's.

#Naming conventions

Name-based matching pairs each low-poly part with its high-poly part, so parts only bake onto themselves. Substance uses the default suffixes _high and _low; the feature is "off by default" and "case sensitive" (Substance 3D Bakers documentation: Matching by Name). Marmoset's quick loader sorts objects into bake groups from their names and is not case sensitive, so "object_HIGH" and "object_low" can be mixed (Marmoset: The Toolbag Baking Tutorial).

A safe habit that works in both: crate_lid_low, crate_lid_high, crate_body_low, crate_body_high. Keep names lowercase and unique. See also naming conventions.

#Anti-aliasing and resolution

Anti-aliasing. Without it, edges in the bake come out jagged. Substance offers subsampling at 2 × 2, 4 × 4 or 8 × 8, noting it "can significantly increase baking time" (Substance 3D Bakers documentation: Common parameters). In Marmoset, "Samples determines the quality of the anti-aliasing" (Marmoset: The Toolbag Baking Tutorial).

Resolution. Substance defaults to 2048 px (Substance 3D Bakers documentation: Common parameters). Bake at least at the final texture size; many artists bake larger and scale down. Detail size matters: Marmoset warns "Details smaller than 1 pixel will not be recorded properly" (Marmoset Toolbag documentation: Baking Tips & Tricks). The 80 Level hard-surface guide advises you to "exaggerate your chamfers" so they read at your normal map resolution, and to bake "as large as possible" (80 Level: Best Practices for Hard Surface Normal Map…). Aliasing along UV borders also drops with higher resolution and UVs aligned to the pixel grid (Substance 3D Bakers documentation: Aliasing on UV seams).

Bit depth. Bake normal maps in 16-bit. The Warframe guide warns that "Upressing from 8bit to 16bit won't help if you've accidentally done it in 8bit" (Warframe Steam Workshop guide: Normal Map Baking). Marmoset notes many renderers still require an 8-bit normal map in the end, but some artists keep 16-bit sources "in order to defer dithering to the final stage" (Marmoset: The Toolbag Baking Tutorial).

#Common mistakes

• Hard edges without UV splits: seam artefacts along the edge (Marmoset: The Toolbag Baking Tutorial).
• Not triangulating: black or X-shaped shading errors in the engine (Substance 3D Bakers documentation: Triangulating before baking; Marmoset Toolbag documentation: Baking Tips & Tricks).
• Wrong green channel or tangent space for the engine. See tangent space and MikkTSpace.
• Overlapping UVs in the baked area.
• Details too small for the texture: they disappear or alias (Marmoset Toolbag documentation: Baking Tips & Tricks).

For diagnosing specific errors, see fixing baking artefacts.

#Further reading and watching