Illuminance and Auto Exposure Key
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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.
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Illuminance Values
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| 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
