PBR lighting questions

[joshezzell]

@OwenWP;618197

For the sun, take the measured lux value and divide by 50 (assumes you are using 100 unreal units = 1 meter scale), that gives you the equivalent directional light intensity for UE4.

This is indeed super bright, and for eye adaptation you will need to adjust the histogram min and max to get your values in a range that the exposure is tracking. The HDR histogram visualizer is helpful here, if you have the right settings you should see a luminance “hump” that is not clipped on either side. I also find that an exposure bias of -1 looks best most situations. From there it is a matter of setting reasonable min and max brightness ranges that preserve contrast at the extremes.

Forgive me for my ignorance on the subject. I am looking into it now using these pages: Lux - Wikipedia and Daylight - Wikipedia

If I divide 32,000 lux (direct sunlight) by 50 it comes out to 640. That seems really high for the directional light. Am I misunderstanding something?

Also, thanks for the info on exposure settings and tweaking.

[Maximum-Dev]

Directional like doesn’t have any unit to it. It’s just a brightness multiplier. Ruining the purpose of PBR.
Physical values for directional and skylight are on the to-do list (if it doesn’t get backlogged) we’ll finally have some proper lighting for outdoors.

[OwenWP]

The sun is very bright, yes. A typical light bulb will not produce any visibly distinguishable illumination in daylight, as you would expect. And the brightest day is about 100,000 times brighter than the brightest night. Fortunately, the eye’s response to brightness is non-linear, and the tone mapper should capture this behavior if the exposure range is set up right.