Importing models
FBX Importer, Rig options

Models

Model files that are placed in the Assets folder in your Unity project are automatically imported and stored as Unity Assets.

A model file can contain a 3D model, such as a character, a building, or a piece of furniture. The model is imported as multiple Assets. In the Project window, the main imported object is a model Prefab. Usually there are also several Mesh objects that are referenced by the model Prefab.

A model file can also contain animation data, which can be used to animate this model or other models. The animation data is imported as one or more Animation Clips.

A Mesh Filter together with the Mesh Renderer makes the model appear on screen
A Mesh Filter together with the Mesh Renderer makes the model appear on screen

Import settings for Meshes

The Import Settings for a model file is displayed in the Model tab of the FBX importer’s Inspector window when the model is selected. These affect the Mesh, its Normals, and the imported Materials. Settings are applied per Asset on disk, so if you need Assets with different settings, make (and rename accordingly) a duplicate file.

Property Function
Meshes
Scale Factor Unity’s physics system expects 1 meter in the game world to be 1 unit in the imported file. If you prefer to model at a different scale then you can compensate for it here. Defaults for different 3D packages are as follows:
.fbx, .max, .jas, .c4d = 0.01
.mb, .ma, .lxo, .dxf, .blend, .dae = 1
.3ds = 0.1
Use File Scale Tick the checkbox to use the default model scaling, or untick to use a custom scaling value for your model. Unity’s physics system expects 1 meter in the game world to be 1 unit in the imported file. If you prefer to model at a different scale then you can compensate for it here.
    File Scale Use this value field to set the scale you want to use for your model.
Mesh Compression Increasing this value reduces the file size of the Mesh, but might introduce irregularities. It’s best to turn it up as high as possible without the Mesh looking too different from the uncompressed version. This is useful for optimizing game size.
Read/Write Enabled If enabled, Mesh data is kept in memory so that a custom script can read and change it. Disabling this option saves memory, because Unity can unload a copy of Mesh data in the game. However, in certain cases when the Mesh is used with a Mesh Collider, this option must be enabled. These cases include:
- Negative scaling (for example, (–1, 1, 1)).
- Shear transform (for example, when a rotated Mesh has a scaled parent transform).
Optimize Mesh Tick this checkbox if you want Unity to determine the order in which triangles are listed in the Mesh.
Import Blendshapes Tick this checkbox if you want Unity to allow BlendShapes to be imported with your Mesh.
Generate Colliders If this is enabled, your Meshes are imported with Mesh Colliders automatically attached. This is useful for quickly generating a collision Mesh for environment geometry, but should be avoided for geometry you are moving.
Weld Vertices Tick this checkbox to combine vertices that share the same position in space. This optimizes the vertex count on Meshes by reducing their overall number. This checkbox is ticked by default.

Note that there is also a WeldVertices parameter on the ModelImporter class, which does the same thing via scripting.

In some cases, you might need to switch this optimization off when importing your Meshes; for example, if you have constructed your Mesh in such a way that you intentionally have duplicate vertices which occupy the same position, and you want to use scripting to read or manipulate the individual vertex or triangle data. .
Swap UVs Tick this checkbox if lightmapped objects are picking up the wrong UV channels. This swaps your primary and secondary UV channels.
Generate Lightmap UVs Tick this checkbox if you want Unity to create a second UV channel to be used for Lightmapping. See documentation on Lightmapping for more information.
Normals & Tangents
Normals Defines if and how normals should be calculated. This is useful for optimizing game size.
Import Default option. Imports normals from the file.
Calculate Calculates normals based on Smoothing angle. If selected, the Smoothing Angle becomes enabled.
None Disables normals. Use this option if the Mesh is neither normal mapped nor affected by realtime lighting.
Tangents Defines if and how tangents and binormals should be calculated. This is useful for optimizing game size.
Import Imports tangents and binormals from the file. This option is available only for FBX, Maya and 3dsMax files and only when normals are imported from the file.
Calculate Default option. Calculates tangents and binormals. This option is available only when normals are either imported or calculated.
None Disables tangents and binormals. The Mesh has no Tangents, so won’t work with normal-mapped shaders.
Smoothing Angle Sets how sharp an edge has to be in order to be treated as a hard edge. It is also used to split normal map tangents.
Split Tangents Enable this if normal map lighting is broken by seams on your Mesh. This usually only applies to characters.
Materials
Import Materials Disable this if you don’t want Materials to be generated. By default, a diffuse Material is used instead.
Material Naming Use this to define how Unity Materials are named:
By Base Texture Name The name of the diffuse Texture of the imported Material that is used to name the Material in Unity. When a diffuse Texture is not assigned to the Material, Unity uses the name of the imported Material.
From Model’s Material The name of the imported Material is used for naming the Unity Material.
Model Name + Model’s Material The name of the model file in combination with the name of the imported Material is used for naming the Unity Material.
Material Search Use this to define where Unity tries to locate existing Materials using the name defined by the Material Naming option:
Local Unity tries to find existing Materials in the “local” Materials folder only (that is, the Materials subfolder, which is the same folder as the model file).
Recursive-Up Unity tries to find existing Materials in all Materials subfolders in all parent folders up to the Assets folder.
Everywhere Unity tries to find existing Materials in all Unity project folders.
Importing models
FBX Importer, Rig options