【Unity】Getting Started with Unity 3D: Mastering 3D Model Import Settings

Overview

In 3D game development, 3D models—characters, environments, props—are the most fundamental assets that compose your game world. These models are typically created in external DCC (Digital Content Creation) tools like Blender, Maya, or 3ds Max, then imported into Unity.

Unity supports various 3D model formats, but the industry standard is FBX (.fbx). FBX can store rich 3D information in a single file: meshes (geometry), UVs (texture coordinates), materials, textures, rigs (skeletons), and animations.

This article covers the essential settings for importing FBX models from DCC tools into Unity and displaying them correctly in your game.

Step 1: Exporting from DCC Tools

Before importing to Unity, you need to export the model correctly from your DCC tool. Using Blender as an example, here are common considerations:

• Scale and Coordinate System: Unity uses meters (1 Unit = 1 meter) with Y-up left-hand coordinate system. Matching your DCC tool settings prevents scale and orientation issues on import. For Blender, typically set Transform > Scale to Apply Scalings: FBX All, Forward to -Z Forward, and Up to Y Up in export settings.
• Apply Transforms: Non-standard scale or rotation values (not (1,1,1) or (0,0,0)) cause unexpected behavior in Unity. Always apply transforms before export (in Blender: Ctrl+A > Apply All Transforms).
• Export Selection: Export only needed objects rather than the entire scene (Limit to: Selected Objects). Cameras and lights are typically created in Unity, so don't include them.

Step 2: Import to Unity and Model Settings

Drag and drop the exported FBX file into your Unity project's Assets folder to import. Selecting the imported model asset shows Model Import Settings in Inspector. Configuration is done across four important tabs: Model, Rig, Animation, and Materials.

Model Tab

Basic mesh settings.

• Scale Factor: Adjusts import scale. Usually 1 is fine if DCC and Unity unit settings match.
• Use File Scale: Uses scale information from the FBX. Usually leave on.
• Read/Write Enabled: Enable if scripts need mesh data access (reading/writing vertices). Disable when not needed to reduce memory usage.
• Generate Colliders: Automatically attaches a Mesh Collider based on mesh shape. Fine for simple shapes, but for complex character models, this hurts performance—usually disable and manually add Capsule Collider etc.

Rig Tab

Sets character rig (skeleton) and animation type. Leave as None for non-character models (environments, weapons, etc.).

• Animation Type:
  • None: Static model with no animation.
  • Legacy: For old Animation component. Don't use unless specifically needed.
  • Generic: For non-humanoid characters (monsters, animals) or animated machinery.
  • Humanoid: For bipedal humanoid characters. Enables Unity's Avatar system for animation retargeting (reusing animations across different models)—very powerful.
• Avatar Definition:
  • Create from This Model: Generates an Avatar (humanoid bone mapping) from this model's rig.
  • Copy from Other Avatar: Uses an Avatar from another model.

When selecting Humanoid, press Configure... to verify and correct Unity's automatic bone mapping.

Animation Tab

Manages animation clips in the FBX. Split clips, set loops, rename, etc.

• Import Animation: Uncheck to skip animation import.
• Clips: If FBX contains multiple animations (e.g., frames 1-30 walk, 31-60 run), add clips with + and specify Start and End frames.
• Loop Time: Enable for looping clips (walk, run, idle).

Materials Tab

Material and texture import settings.

• Location:
  • Use Embedded Materials: Uses materials embedded in FBX. Can't edit until extracted as Unity materials.
  • Use External Materials (Legacy): Old method. Usually don't use.
• Material Creation Mode: Import via MaterialDescription recommended.
• Extract Textures... / Extract Materials...: Extracts embedded textures/materials as editable assets (.png, .mat, etc.) in project. Usually do this once after import to enable Unity material adjustments.

Summary

Understanding import settings is essential for correctly using externally created 3D models in Unity.

• Match scale and coordinate system to Unity in your DCC tool, apply transforms, then export as FBX.
• Configure Model Import Settings tabs based on model type.
• Model tab: Scale, collider generation, etc.
• Rig tab: Set Humanoid or Generic for characters.
• Animation tab: Split and configure animation clips.
• Materials tab: Extract materials/textures for editing.

Once configured correctly, you can place models in scenes, animate them, and have them perform as important actors in your game.