The Level Editor exposure control uses an EV100 slider and a game settings checkbox in the View Mode dropdown menu.
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When Game Settings is enabled, the Level Viewport uses the in-game settings configuration for exposure behavior (see section below this). Otherwise, the EV100 slider enables user-override with a range of -10 to 20, supporting very dark to very bright scenes using realistic scene illumination.
For other viewports than the level viewport, the "Game Settings" check-box is replaced by an "Auto" check-box and implements an automatic exposure behavior.
In 4.19 and later releases, some settings have been renamed, and the previous settings you used are compatible.
The in-game settings for exposure are controlled within Post Process settings. When selecting between different Metering Modes
, settings relevant to the selected method are editable while ones that are not are grayed out.
Choose between the following Metering Modes:
- Auto Exposure Histogram constructs a 64 bin histogram enabling finer control over auto exposure with advanced settings.
- Auto Exposure Basic is a faster method that computes single values by down sampling.
- Manual enables the use of Camera settings within the Post Process Volume to control exposure rather than the Exposure settings.
Manual Metering Mode
Manual metering mode uses the value of the camera exposure defined by the Post Process Camera settings for Shutter Speed (1/t), ISO (S), and Aperture (N).
The formula used to compute the camera exposure scale is:
- Exposure = 1 / (1.2 * 2^EV100)
- EV100 = log2( N²/t * 100/S )
here defines the relationship between the scene surface luminance (L in cd/m²) and pixel brightness (B) before the tonemapper and exposure compensation (see below) are applied:
This can be verified by disabling the Tonemapper through the Show Flags and inspecting the scene brightness with the pixel inspector. Note that the EV100 editor overrides directly sets the EV100 in this equation.
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The Exposure Compensation (ExpComp) defines an additional scale of 2^ExpComp on top of the exposure computed from the current metering mode, except when using the EV100 Editor overrides.