# convertUnitsToMeters An option for whether to automatically scale the scene’s contents. ``` static let convertUnitsToMeters: SCNSceneSource.LoadingOption ``` ## Discussion The value for this key is an object containing a floating-point value. The default value is `nil`, specifying no unit conversion. SceneKit’s physics simulation works best when one unit in the scene’s coordinate space corresponds to one meter in the physics world. When you load elements from scene files, provide a value for this key specifying the number of meters (in the coordinate space of the loaded scene) for each unit in the scene coordinate space of the elements to be loaded. For example, an artist might design a game character using a scale where one unit is a US foot. To load this model for use in SceneKit’s meter-based coordinate space, specify a value of `0.3048` for this key. This option has no effect for assets compressed by Xcode. Instead, use Xcode itself to convert units when compressing the assets. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)