Hi,
I’m currently evaluating a physically based lighting workflow in UE5 and would like to understand what practical benefits it offers compared with using lower, game-scaled lighting values.
My goal is not strict 1:1 physical accuracy. I’m mainly interested in whether real-world units can serve as a consistent reference scale for lighting and LookDev.
For example, a fully physical setup might use real-world sunlight lux values, physically plausible HDRI luminance, lumens/candelas for artificial lights, and EV100-based exposure.
In an actual game, however, we often need to compress this range for gameplay and readability.
In my current setup, for example, I may use roughly 2,000 lux for the Directional Light plus HDRI/Sky Light contribution, with a deliberately limited exposure range to prevent excessive indoor/outdoor adaptation.
The issue is that once the exposure range is compressed, realistic indoor light values such as a 4,000 lm fixture may no longer appear strong enough. Artificial lights and emissives may therefore require an additional gameplay multiplier.
So I’m curious about Epic’s recommended approach:
• Is there still an advantage to using physically based units as the underlying reference scale when the final lighting range is intentionally compressed?
• Does this help maintain predictable relationships between sunlight, HDRI/Sky Light, artificial lights, emissives, and exposure across different maps?
• Is it useful for consistent LookDev and collaboration between multiple artists?
• With Lumen, are there benefits or drawbacks to keeping lighting values within a physically meaningful scale?
• If artificial lights require a gameplay multiplier, is it better to preserve the physical value as a baseline and apply the multiplier separately?
Essentially, I’m wondering whether the primary benefit of physically based lighting in a real-time game is absolute physical accuracy, or whether it can instead be viewed as a shared and predictable reference system that can later be compressed or artistically adjusted.
I’d be very interested to hear how Epic approaches this in production.