Art Asset best practice guide
FBX export guide

How do I import models from my 3D app?

There are two ways to import 3D models into Unity:

  • Drag the 3D model file from your file browser straight into the Unity Project window.
  • Copy the 3D model file into the Project’s Assets folder.

Select the file in the Project view and navigate to the Model tab in the Inspector window to configure import options. See documentation on Models for more information about import options.

Unity supports importing models from most popular 3D applications. For more guidance on how to import from specific 3D packages, see the following pages:

Textures

You must store Textures in a folder called Textures, placed inside the Assets folder (next to the exported Mesh) within your Unity Project. This enables the Unity Editor to find the Textures and connect them to the generated Materials. For more information, see documentation on Importing Textures.

3D formats

Importing meshes into Unity can be achieved from two main types of files:

  1. Exported 3D file formats, such as .FBX or .OBJ
  2. Proprietary 3D application files, such as .Max and .Blend file formats from 3D Studio Max or Blender for example.

Either should enable you to get your meshes into Unity, but there are considerations as to which type you choose:

Exported 3D files

Unity can read .FBX, .dae (Collada), .3DS, .dxf and .obj files, FBX exporters can be found here and obj or Collada exporters can also be found for many applications

Advantages:

  • Only export the data you need
  • Verifiable data (re-import into 3D package before Unity)
  • Generally smaller files
  • Encourages modular approach - e.g different components for collision types or interactivity
  • Supports other 3D packages whose Proprietary formats we don’t have direct support for

Disadvantages:

  • Can be a slower pipeline for prototyping and iterations
  • Easier to lose track of versions between source(working file) and game data (exported FBX for example)

Proprietary 3D application files

Unity can also import, through conversion: Max, Maya, Blender, Cinema4D, Modo, Lightwave & Cheetah3D files, e.g. .MAX, .MB, .MA etc.

Advantages:

  • Quick iteration process (save the source file and Unity reimports)
  • Simple initially

Disadvantages:

  • A licensed copy of that software must be installed on all machines using the Unity project
  • Files can become bloated with unnecessary data
  • Big files can slow Unity updates
  • Less validation, so it is harder to troubleshoot problems

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 may 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 may 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.

FBX Importer Inspector: Model tab
FBX Importer Inspector: Model tab
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. Defaults for different 3D packages are as follows:
0.01: .fbx, .max, .jas, .c4d
0.1: .3ds
1.0: .mb, .ma, .lxo, .dxf, .blend, .dae or anything else
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.
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.

See also

Art Asset best practice guide
FBX export guide