The minimum exposure value to use in tone mapping.
- iOS 10.0+
- macOS 10.12+
- tvOS 10.0+
- watchOS 3.0+
When using a High Dynamic Range (HDR) camera, SceneKit applies a process called tone mapping to translate the wide range of luminance values in the visible scene to the narrower range of brightness values that can be shown on a display. SceneKit determines a tone mapping curve from the
white properties, along with a measure of scene luminance.
Exposure values are exponential: a value of
1 doubles brightness, a value of
2 quadruples brightness, a value of
-1 halves brightness, and so on. The default value is
15. Decreasing the value causes brighter portions of the scene to become over-exposed (uniformly white, losing definition). Increasing the value adds more dynamic range for brighter portions of the scene; however, a greater breadth of difference between the minimum and maximum exposures decreases contrast.
This property has no effect if the
wants value is