You can create complex Models for game characters, terrains, and other environment objects outside of Unity and import them. For example, you can create SpeedTree Models for your terrain and create GameObjects in Blender or Autodesk® Maya®.
Unity supports FBX files which you can export from most 3D modeling applications. However, SketchUp and SpeedTree do not support exporting to FBX. For information on how to work with those proprietary file formats, see the documentation on SketchUp Settings and SpeedTree.
Always export Models from your 3d modeling application to FBX instead of directly saving your application files in your Unity Project. Don’t use native file formats directly in production. Even if you use the proprietary application files directly in your Project, Unity converts them to the FBX format first before importing them.
Before starting to create anything in your 3D modeling applications, read the guidelines below to ensure the best results:
Unity’s physics and lighting systems expect 1 meter in the game world to be 1 unit in the imported Model file.
The defaults for different 3D packages are as follows:
When importing Model files into Unity from a 3D modeling application with a different scaling factor, you can convert the file units to use the Unity scale by enabling the Convert Units option.