Illuminance and Auto Exposure Key
Also known as luminous flux density, illuminance is the total amount of visible light falling on a point on a surface from all directions above the surface in a given time. Proper illuminance values ensures the environment lighting in your level closely models real-world values. Besides simply having good ratios between light and dark, accurate illuminance values ensure that tone-mapping, and eye adaptation works optimally.
The following table lists real-world illuminance values, expressed in luminous flux (lux). Lux is the unit of illuminance and luminous emittance, measuring lux per unit area, and equal to one lumen per square meter.
Illuminance Values
| Real-world illuminance | Lux Value | Uniformity Ratio | Artistic Interpretation |
|---|---|---|---|
| Full moon | 0.25 | 0.00005 | - |
| Living room | 50 | 0.01 | - |
| Clear sunrise | 400 | 0.08 | - |
| Office | 500 | 0.1 | - |
| TV studio | 1,000 | 0.2 | - |
| Overcast day | 15,000 | 3.0 | ~ 1.5 |
| Indirect sunlight (in shadow) | 20,000 | 4.0 | ~ 2.0 |
| Direct sunlight | 100,000 | 20.0 | ~ 10.0 |
The Auto Exposure Key setting controls the amount of light exposure and determines whether the tone-mapped image appears relatively bright or dark. This setting is calculated automatically from the average scene illuminance, which is why it is important to use standard real-world illuminance levels. For other settings that affect the tone mapping of a scene, see HDR Settings.
Lumberyard's auto-exposure mode works in exposure value (EV) units and can be enabled using the r_HDREyeAdaptationMode console variable.
The following settings are used to achieve the desired illuminance in an environment level. See Setting Daytime Atmospheric Effects for more information.
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Sun color
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Sun color multiplier
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Sun intensity
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Sun intensity multiplier
