Legacy Documentation: Version 2018.1 (Go to current version)
Model Import Settings window
Rig tab
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Model tab

The Import Settings for a Model file appear in the Model tab of the Inspector window when you select the Model. These affect the Mesh and its Normals. Unity uses these settings to import each Asset, so if you can adjust any settings to apply to different Assets in your Project.

Import settings for the Model
Import settings for the Model
Property Function
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.

The 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 Use the model scaling defined in the model file, or uncheck to set a custom Scale Factor value for your model.
File Scale Set a custom scale for your model. Only available when Use File Scale is checked.
Mesh Compression Set the level of compression ratio to reduce the file size of the Mesh. Increasing the compression ratio lowers the precision of the Mesh by using the mesh bounds and a lower bit depth per component to compress the mesh data.

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.
Off Don’t use compression.
Low Use a low compression ratio.
Medium Use a medium compression ratio.
High Use a high compression ratio.
Read/Write Enabled When this option is enabled, Unity uploads the Mesh data to GPU-addressable memory, but also keeps it in CPU-addressable memory. This means that Unity can access the mesh data at run time, and you can access it from your scripts. For example, if you’re generating a mesh procedurally, or if you want to copy some data from a mesh. When this option is disabled, Unity uploads the Mesh data to GPU-addressable memory, and then removes it from CPU-addressable memory.

In most cases, you should disable this option to save runtime memory usage. For information on when to enable Read/Write Enabled, see Mesh.isReadable.
Optimize Mesh Let Unity determine the order in which triangles are listed in the Mesh. Unity reorders the vertices and indices for better GPU performance.
Import BlendShapes Allow Unity to import BlendShapes with your Mesh.

Note Importing blendshape normals requires smoothing groups in the FBX file.
Generate Colliders Enable to import your Meshes 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.
Keep Quads Enable this to stop Unity from converting polygons that have four vertices to triangles. For example, if you are using Tessellation Shaders, you may want to enable this option because tessellating quads may be more efficient than tessellating polygons.

Unity can import any type of polygon (triangle to N-gon). Polygons that have more than four vertices are always converted to triangles regardless of this setting. However, if a mesh has quads and triangles (or N-gons that get converted to triangles), Unity creates two submeshes to separate quads and triangles. Each submesh contains either triangles only or quads only.

Tip: If you want to import quads into Unity, you have to use editable poly in 3ds Max.
Index Format Define the size of the Mesh index buffer.

Note: For bandwidth and memory storage size reasons, you generally want to keep 16 bit indices as default, and only use 32 bit when necessary, which is what the Auto option uses.
Auto Let Unity decide whether to use 16 or 32 bit indices when importing a Mesh, depending on the Mesh vertex count. This is the default for Assets added in Unity 2017.3 and onwards.
16 bit Use 16 bit indices when importing a Mesh. If the Mesh is larger, then it is split into <64k vertex chunks. Assets that already exist in Projects made in Unity 2017.2 or previous versions will use this setting.
32 bit Use 32 bit indices when importing a Mesh. If you are using GPU-based rendering pipelines (for example with compute shader triangle culling), using 32 bit indices ensures that all Meshes use the same index format. This reduces shader complexity, because they only need to handle one format.
Weld Vertices Combine vertices that share the same position in space. This optimizes the vertex count on Meshes by reducing their overall number. This option is enabled by default.

In some cases, you might need to switch this optimization off when importing your Meshes. For example, if you intentionally have duplicate vertices which occupy the same position in your Mesh, you may prefer to use scripting to read or manipulate the individual vertex and triangle data.
Import Visibility Import the FBX settings that define whether or not MeshRenderer components are enabled (visible). See Importing Visibility below for details.
Import Cameras Import cameras from your .FBX file. See Importing Cameras below for details.
Import Lights Import lights from your .FBX file. See Importing Lights below for details.
Preserve Hierarchy Always create an explicit prefab root, even if this model only has a single root. Normally, the FBX Importer strips any empty root nodes from the model as an optimization strategy. However, if you have multiple FBX files with portions of the same hierarchy you can use this option to preserve the original hierarchy.

For example, file1.fbx contains a rig and a Mesh and file2.fbx contains the same rig but only the animation for that rig. If you import file2.fbx without enabling this option, Unity strips the root node, the hierarchies don’t match, and the animation breaks.
Swap UVs Swap UV channels in your Meshes. Use this option if your diffuse Texture uses UVs from the lightmap. Unity supports up to eight UV channels but not all 3D modeling applications export more than two.
Generate Lightmap UVs Creates a second UV channel 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 Import normals from the file. This is the default option.
Calculate Calculate normals based on Smoothing Angle (below).
None Disable normals. Use this option if the Mesh is neither normal mapped nor affected by realtime lighting.
Normals Mode Define how the normals are calculated by Unity. This is only available when Normals is set to Calculate.
Unweighted Legacy The legacy method of computing the normals (prior to version 2017.1). In some cases it gives slightly different results compared to the current implementation. It is the default for all FBX prefabs imported before the migration of the Project to the latest version of Unity.
Unweighted The normals are not weighted.
Area Weighted The normals are weighted by face area.
Angle Weighted The normals are weighted by the vertex angle on each face.
Area and Angle Weighted The normals are weighted by both the face area and the vertex angle on each face. This is the default option.
Smoothing Angle Control whether vertices are split for hard edges: typically higher values result in fewer vertices.

Note: Use this setting only on very smooth organics or very high poly models. Otherwise, you are better off manually smoothing inside your 3D modeling software and then importing with the Normals option set to Import (above). Since Unity bases hard edges on a single angle and nothing else, you might end up with smoothing on some parts of the Model by mistake.

Only available if Normals is set to Calculate.
Tangents Define how vertex tangents should be imported or calculated. This is only available when Normals is set to Calculate or Import.
Import Import vertex tangents from FBX files if Normals is set to Import. If the Mesh has no tangents, it won’t work with normal-mapped shaders.
Calculate Tangent Space Calculate tangents using MikkTSpace. This is the default option if Normals is set to Calculate.
Calculate Legacy Calculate tangents with legacy algorithm.
Calculate Legacy - Split Tangent Calculate tangents with legacy algorithm, with splits across UV charts. Use this if normal map lighting is broken by seams on your Mesh. This usually only applies to characters.
None Don’t import vertex tangents. The Mesh has no tangents, so this doesn’t work with normal-mapped shaders.

Importing visibility

Unity can read visibility properties from FBX files with the Import Visibility property. Values and animation curves can enable or disable MeshRenderer components by controlling the Renderer.enabled property.

Visibility inheritance is true by default but can be overridden. For example, if the visibility on a parent Mesh is set to 0, all of the renderers on its children are also disabled. In this case, one animation curve is created for each child’s Renderer.enabled property.

Some 3D modeling applications either do not support or have limitations regarding visibility properties. For more information, see:

Importing cameras

Unity supports the following properties when importing Cameras from an .FBX file:

Property: Function:
Projection mode Orthographic or perspective. Does not support animation.
Field of View Supports animation.
Near and Far Clipping Plane distance Does not support animation. When exporting from 3ds Max, enable the Clip Manually setting; otherwise the default values are applied on import.

Note: Targeted cameras are not supported.

Importing lights

The following Light types are supported:

  • Omni
  • Spot
  • Directional
  • Area

The following Light properties are supported:

Property: Function:
Range The FarAttenuationEndValue is used if UseFarAttenuation is enabled. FarAttenuationEndValue does not support animation.
Color Supports animation.
Intensity Supports animation.
Spot Angle Supports animation. Only available for Spot lights.

Note: In 3ds Max, the exported default value is the value of the property at the current selected frame. To avoid confusion, move the playhead to frame 0 when exporting.


Some 3D modeling applications apply scaling on light properties. For instance, you can scale a spot light by its hierarchy and affect the light cone. Unity does not do this, which may cause lights to look different in Unity.

The FBX format does not define the width and height of area lights. Some 3D modeling applications don’t have this property and only allow you to use scaling to define the rectangle area. Because of this, area lights always have a size of 1 when imported.

Targeted light animations are not supported unless their animation is baked.

  • 2018–08–23 Page amended with limited editorial review

  • 2018–04–25 Page amended with limited editorial review

  • 2017–12–05 Page amended with limited editorial review

  • 2017–09–04 Page amended with limited editorial review

  • Existing (pre Unity 5.6) functionality of Keep Quads first documented in User Manual 5.6

  • Normals Mode, Light and Camera import options added in Unity 2017.1 NewIn20171

  • Materials tab added in 2017.2 NewIn20172

  • Index Format property added in 2017.3 NewIn20173

  • Updated description of read/write enabled setting and reorganized properties table, to match improvements in Unity 2017.3 NewIn20173

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Model Import Settings window
Rig tab