Hi there,
Can someone tell me please what manual exposure compensation matches real world light values (candela, lumens) the closest? Or what exposure levels do you work with?
Thanks
Stu
Im constructing a building and want to match the real world lights values to the unreal engine model as best as I can
You can read more about it here: Auto Exposure (Eye Adaptation) | Unreal Engine 4.27 Documentation. The documentation doesn’t specify if it uses candelas or lumens, it is closer to aperture from a camera and gamma controlling.
Manual Algorithm
The Manual metering mode allows the user to select a single, fixed exposure value that is unaffected by the luminance in the scene. If Apply Physical Camera Exposure is disabled in the post process settings, the exposure value will be linear brightness:
Exposure = 1/(2^(EV100 + Exposure Compensation))If Apply Physical Camera Exposure is applied, EV100 is calculated as the following formula. Otherwise, it is 0.
EV100 = log2(Aperture^2 / Shutter Speed * 100/ISO)Exposure in the following formula defines the relationship between the scene surface luminance (L, which is measured in cd/m2) and pixel brightness (B) before the tonemapper and exposure compensation are applied.
B = Exposure * LYou can verify this formula’s result by disabling the tonemapper through the viewport show flags (Show > Post Processing), and inspect the scene brightness using the Pixel Inspector. Also note that the editor EV100 override setting directly sets the EV100 exposure used in this equation.
When you are placing lights in Unreal Engine you are able to select the unit / measurement.
1 Like