Illuminance and Auto Exposure Key - Lumberyard User Guide

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.

  • Sun color

  • Sun color multiplier

  • Sun intensity

  • Sun intensity multiplier