What is checked, and against which numbers
Roles from names. The file name is lower-cased, separators become _, and the first matching token wins, most specific first: packed (orm, arm, rma, mra, maskmap, mask), albedo (albedo, basecolor, diffuse, color …), normal (normalgl, normaldx, normal, nrm, n), roughness, smoothness (gloss), metallic, AO (ao, occlusion, ambientocclusion), height (height, displacement, bump), emission, opacity, specular. Tokens of one or two letters (_n, _m, _r) count as low confidence. Every role is a drop-down, so you correct a wrong guess instead of renaming files.
Workflows decide what is missing. Separate maps (glTF / generic): albedo required; normal, roughness, metallic recommended. Unity HDRP: albedo and the mask map required, normal recommended. Unity URP: albedo required; normal and metallic recommended. Godot ORM and Unreal ORM: albedo required; normal and the ORM texture recommended — and when roughness and metallic are present but the ORM is not, you get "pack available" instead of a bare "missing". A roughness map satisfies smoothness and the other way round.
Measurements, not guesses. A single-channel role (roughness, metallic, AO, height, opacity) stored as RGB is "grey stored as RGB" when no texel's channels differ by more than 2, and "channels differ" (probably packed) when they do. A normal map is decoded texel by texel: a sample is off-unit when its length is more than 0.12 from 1; the map passes when at most 1 % of samples are off-unit and no blue is below 128 (a vector pointing into the surface). A map assigned another role that passes the normal-map test (≤ 5 % off-unit, ≤ 0.1 % negative blue) is flagged "looks like a normal map".
Power of two is a warning, not an error. glTF 2.0 says clients SHOULD resize non-power-of-two textures on platforms with limited support when the sampler repeats or uses mipmaps; Unity's importer has a Non Power of 2 option that scales such textures. Whether that matters depends on your target, so the validator reports it and leaves the decision to you.
- Workflow
- The set of maps an engine's material expects, including how they are packed.
- Set name
- What is left of the file name after the role token; different set names in one drop trigger "naming inconsistent".
- Off-unit sample
- A decoded normal whose length differs from 1 by more than 0.12.
- Power of two
- A size of 2ⁿ pixels: 256, 512, 1024, 2048 …