Unreal's importer does more for you than Unity's, which is helpful until it does something you did not intend.
Scale and orientation
Unreal works in centimetres — one unit is one centimetre — and is Z-up. Most DCC tools are Y-up, and the FBX importer handles the conversion, but a model that arrives rotated ninety degrees usually means the axis conversion was applied twice.
Static mesh settings
- Generate Lightmap UVs. On by default. Creates a second UV channel for baked lighting. If you author your own lightmap UVs, turn it off — Unreal's generated ones are adequate rather than good.
- Auto Generate Collision. Creates a simple collider. Convenient for props, wrong for anything with a hollow. See collision meshes.
- Build Nanite. Whether this mesh becomes a Nanite mesh. Powerful and not universal — see Nanite.
- Combine Meshes. Merges separate objects in the file into one asset. Useful for a prop split across parts; destructive if the parts needed to move.
Materials
Unreal creates a material per imported material slot, and they are almost always placeholders. The real workflow is a small set of master materials with parameters, and material instances per asset. That is not a stylistic preference — instances share a compiled shader, and a project with hundreds of unique materials pays for hundreds of shader permutations.
Skeletal meshes
- Import a skeleton or reuse an existing one. Reusing is what makes animation retargeting straightforward.
- Import Morph Targets if the mesh has blend shapes; they are off by default and their absence is a common surprise.
- Physics Asset is generated automatically and is usually a reasonable starting point, unlike auto collision on static meshes.
Textures
- sRGB off for anything carrying data rather than colour.
- Compression Settings must match the map type — Normalmap for normals, Masks for packed ORM textures — using the default on a mask texture costs quality and memory both.
- Virtual Textures for very large texture sets, at the cost of some complexity.