How much to scale the tree model compared to what is in the imported SpeedTree model file.
In the Unity Editor, the SpeedTreeImporter provides a dropdown with the following unit conversion options, which drive the scaleFactor value:0 - LeaveAsIs : 1.0
1 - FeetToMeters : 0.3048
2 - CentimetersToMeters : 0.01
3 - InchesToMeters : 0.0254
4 - CustomConversion : user specified value
By default, the SpeedTree Modeler exports units in feet. Because Unity's default units are meters, the default value for scaleFactor is set to 0.3048.